My own opinion is that decisions to close a question should be based on only the question and not the person asking it. In the above linked question, it was asking about gaps in floor boards. Answers to this question are useful to other homeowners experiencing the same problem and so the question should be considered on topic.
Questions on the site should be of the form
How do I solve this problem?
with sufficient detail about the problem of course.
Then the answer is how to solve that problem, be it
Do this procedure
Buy this product
This should be the same across the network, the only problem being that on some sites people abuse the system so questions ...
If a question is off topic it's off topic regardless of it's age.
We can't be expected to review every question as it gets posted and off topic questions will slip through occasionally. In this case when an old, off topic question comes to your attention then do one of the following (depending on your reputation):
If you have less than 3,000 reputation ...
No, questions dealing with resale value are not typically considered on topic. Prices, preferences, and market values change far too much too quickly. These types of questions will be out of date fairly quickly, and so will require constant updating.
While cost and resale value are a part of most projects, it's not the part of the project we focus on. ...
This is not the place for that type of question, and I don't know of any SE sites where that question would be on topic.
You should contact a local real estate agent, as they'll have more detailed information based on your specific location.
My own opinion is that we stay with the site's core audience, people that are handy with fishing wires, fixing plumbing, and swinging hammers. A question about how to install some home automation device and connect it to the house is on topic since they're dealing with cutting holes in walls, electrical wiring, etc, which has always been on topic here. A ...
This sort of question should be off topic.
Recommendation questions are hard and it's no surprise that most sites don't allow them. Those that do have very strict rules about what makes a good question.
There are a number of problems with this type of question:
They attract spam.
They go out of date very quickly.
Did I mention they attract spam?
I agree, these sort of questions should be off-topic.
As you point out they're not installation questions nor are they trouble shooting questions.
As to how it got so many upvotes - they were given on the site it was migrated from.
I'm not so sure... when I first saw the question you linked to, I thought he was talking about silicone gel, that you often see for cookware like muffin tins, cake pans and so on, which would make it off topic. Other household uses of silicone make less sense to me: I can't imagine anyone would scrape up their discolored silicone caulk, heat it and reapply ...
Even time can be highly variable. Is there fire blocking in the wall preventing wires from being easily fished? Is the breaker panel at capacity requiring an upgrade to the entire panel? Is the construction older with the potential for aluminum or even knob and tube? Are they including cleanup, drywall patching, or even painting? Is the estimate for one ...
It would definitely be on-topic: we have several questions about repairing tools or powertools already (there's some overlap in the queries because there are a few questions with both tags) and several more about drill presses.
I'd also say that it's more appropriate for Home Improvement than for Woodworking because a drill press can be used on other ...
Upholstery is (almost) entirely used on furniture and other items that are not part of the house. This makes it decidedly off-topic here, as an arts & crafts type of question. Questions using the upholstery tag should be closed and/or retagged and the tag allowed to die.
I think it depends on the context. In your situation, it sounds to me like it could be considered on topic. To me, it's quite similar to this question What is better for a roof plywood or osb. You've observed some aspect of construction, and are curious why it's done that way. To me, this seems on topic.
If you were asking how to do something on an ...
I think asking about what type of wire to run, how many to run, etc is a better question for SuperUser, as that stuff is ultimately dependant on what you want to do and what equipment is being connected.
Asking about how to physically run the wire is better suited to DIY. Examples off the top of my head would be questions involving: conduit, code compliance,...
I would say wiring questions are a better fit here. Once you start connecting and configuring devices I'd take any problems to SuperUser.
We already have some good questions here under data-wiring:
What should I consider regarding LAN wiring before building a house?
How do I run ethernet cable through a wall cavity?
What should I use to secure/organize ...
That sounds like a useful addition to the FAQ (and indeed about page) - perhaps replacing some (or indeed all) of the bullet points we currently have.
I think it defines the distinction between what's on and off topic quite clearly. There will be questions where there is dispute over which side of the line they lie, but hopefully it should be more obvious ...
The lawn-mower tag here includes questions about electric mowers, the self propel mechanism, the blades of the mower, the flywheel, and other topics not necessarily specific to a small engine. For small engine repair, the most appropriate is probably Mechanics.SE's small engine tag.
Using the linked Wikipedia article as a guide:
Potentially on topic, when asking about the use and maintenance of said tools.
Off topic. See Seasoned Advice.
Off topic, unless asking about the maintenance, repair, or installation of washers and dryers.
There have been several woodworking proposals on Area 51 over the years. I know I've followed at least three of them, and there may have been more that I didn't notice because I don't always visit Area 51 regularly. I do know that other frequent visitors to this site followed some of those earlier woodworking proposals, so there is some interest.
From what ...
Questions about how to use a tool (which could be used for home improvement) are considered on-topic here. I'd recommend including a photo and steps you've taken to try to use it. Of course, if it's an old drill and you've tried the obvious, it may just be broken.
This wouldn't be a good question for the site. It's not about how to improve your home, rather it's about how to take potentially legal action against a contractor. The answer depends on where you live and I don't know of any SE site where it would be on topic.
My personal dividing line is if the question invites products as a potential answer, making users unfamiliar with the site likely to be accidentally labeled as a spammer. The site feels more inviting if new users aren't encouraged to post content that would get them banned from the site after a single mistake.
Even the first linked question I personally see ...
I would say yes. It is just another tools used in a house. As long as you were comparing specs and not brands it would be just like 100s of other questions asked here. Air filters are all about specs so this should be really easy.
How to hack my garage power feed by bridging CBs? should definitely be off-topic.
How do I increase the fill level on my washing machine? is (should be) on topic.
IMO disallowing "Operation of major appliances or questions regarding small appliances." is wrong. It directly conflicts with: ('operation' is, which button do I press?)
Which tools, materials,...