At some point, there were an equal number of average and bad programmers on Stack Overflow as there were average and good programmers on Stack Overflow. But Stack Overflow does not reward people for being good programmers. SO rewards actions that game the system. And when SO points became a kind of currency for finding jobs ("I have five thousand points on SO!" on a resume), it skewed the userbase heavily in the direction of "game the system for more points". So you had average, bad, and awful programmers gaming the system and earning points, but because they are just terrible at what they do and the quality of all of their output is awful, this had the effect of driving away the average, good, and excellent programmers away from Stack Overflow.
At some point, the whole of SO shifted, and what you had was a bunch of point-chasing, terrible "programmers" gaming the system for points. There are actually a substantial number of reasonable questions which are not even slightly related to the questions they're closed as duplicates of. But in the eyes of these shit-awful "programmers" they're similar enough to close. Stack Overflow is on its way out. It has served its purpose in life, and perhaps will remain somewhat relevant to the kinds of enormous enterprises that hire shit-awful programmers with their Stack Overflow points on their resumes. But all the reasons it was originally attractive are now gone, as are the majority of the excellent programmers that made it interesting.
I'm not sure if Quora is its replacement, and I'm not sure what the next big place where excellent programmers go to share insights looks like. But it's not Stack Overflow.
* The question is closed as a duplicate, but the question it's a duplicate of is subtly different enough to be completely irrelevant to me.
* The question is closed as a dupilcate, but there's no link to what it's a duplicate of.
* The question is closed as a duplicate, but there are no good answers to the question it's a duplicate of.