Duplicate questions getting re-answered

Question

This may come off as a rant - and I guess maybe it is one (at least a little bit), but here goes...

Why do users re-answer questions which are clearly and obviously duplicates instead of flagging them as duplicates?
I can easily understand a new user not knowing that minor variations on what boils down to the same question get asked repeatedly, but we quite often have long-standing experienced users churning out the same answers to the same questions over and over.

For example, a recent question: How to revitalize wood screw hole where screw won't stay tight?
with a selection of duplicates:

• How do I rehang a wooden door with worn screw holes?
• What are some effective methods to fix a worn out screw holes of a door hinge?
• What do I need to do to fix stripped door hinge screw holes?
• Do I need a wood hardener for worn door hinge screw holes?
• fixing stripped screw in soft-wood door frame?
• How to mount screw in a worn out hole
• How can I repair screws in furniture with stripped holes?
• and more of the same ....

How do we encourage those among us who really should know and recognize a duplicate question when they see it so use the duplicate system which is in place?
Is it too difficult to find the duplicate(s)?
What else hinders us from using the duplicate system?

_{This behavior is certainly not unique to DIY - I often see it on Electronics too.}

Answer 1

Partial answer, from my own experience ...

Is it too difficult to find the duplicate(s)?

Yes. SE's question/answer search feature feels extremely primitive and it's difficult to find similar related questions and answers on a particular topic.
Putting the same search terms into google and limiting the search to SE sites is more likely to give me useful results than SE's own search.
For an answer which maybe only takes a paragraph or so it's probably quicker and easier to just re-write the same answer I or someone else wrote a couple of weeks or months back than it would be to wrestle SE's search into submission and show me the duplicates I know exist somewhere...