I see a developing copyright problem on DIY, which if not nipped in the bud could cause problems:
In an effort to help, the DIY answer community has at times made extensive use of images and text they did not create, and often without attribution.
Essentially all creative works, including images and text posted to the web, are covered by an automatic copyright, unless the author specifies something like a Creative Commons licence. Even then, attribution of the source is generally required, and often missing on DIY SE. It does depend a bit on the country, but not that much since the Berne Convention regularizes a lot of this.
Basic "fair use" conventions allow quoting copyrighted works for reference or for criticism, but not in a way that replaces the need for the original. An example of a replacement for the need of the original is: https://diy.stackexchange.com/a/39806/5960 . Where an original summary with a link to the NFPA would clearly be fair use, the full code section was quoted, and that would likely be over the line if adjudicated.
In the case of codes & standards, the code organizations derive their funding from the sale of the code books. One can argue this model is wrong, but is presently the model. The NFPA for example has sued republishers of copyrighted code books multiple times (for example here's a complaint against Public Resource ). NFPA has responded to criticism by making crippled versions of the code available online, with the easier to use versions requiring a payment. Professionals are expected to pay, but everyone can read.
Beyond the above, when quoting code books, several dangers arise. A person may read the code quote without understanding which jurisdiction it applies to. And should a safety change take place, the DIY site will have old information (for example when antifreeze in sprinkler systems was found to be explosive).
In the case of illustrations, photos, or diagrams, the original author has the ownership of those works, and the right to place associated advertising. By "lifting" those images for Stack Exchange, that original author is deprived of those rights.
Global sites like Pinterest sidestep this issue by claiming they help people discover the original source of the creative work. DIY posts generally do not offer a link to the original, and often replace the need to read the original creative work. That's both contrary to copyright law, and doing a disservice to the original authors who are cut out from reaping the rewards of their labor.