So many of the responses here are effectively identical to complaints folks had about Stack Overflow 3 months, 6 months, a year after it was launched.

They were valid complaints then, and they've valid now.

But... They don't answer this question, which is predicated on SO losing prominence - if poor moderation, rude answers or "duplicates" were enough to torpedo the site, why did it ever gain any prominence at all?

To understand this, we need to look at the state of the 'Net back in 2008, when the idea behind Stack Overflow was conceived and when the first version of the site launched[1].

16 years ago...

- ...USENET was still (barely) around and in use. A non-trivial number of folks hanging around on SO in the early days were old newsgroup regulars for various platforms / tech. SO offered them a welcome reprieve from the by-then-crushing tedium of spam and endless repetition that had pretty much killed USENET by then, as well as a larger audience.

- ...General-purpose "programming sites" (forums, blogs, article repositories, snippet sites) were still very much a thing. CodeProject, CodeGuru, w3schools, etc. For the most part, they had inherited all the problems of USENET and introduced new problems of their own. Again, SO offered a reprieve.

- ...Then as now, special-purpose forums / mailing lists / IRC rooms were collecting an awful lot of "original expertise" for various projects. Then as now, these were mostly useless for disseminating this information; that job fell on folks willing to spend crazy amounts of time soaking it up and then summarizing it in documentation, tutorials, FAQs, or actual books. Most of which didn't get read by the folks who most needed it[2]. So the actual dissemination was handled by the handful of people who did read these resources, via answers to questions on USENET or other major programming sites. The same questions, over and over and over again, until finally years into it some bit of critical information finally entered the public consciousness and questions tailed off.

- ...Google was really, really good at finding information. But information was often not structured in a way that was friendly to Google. Yes, as crazy as it sounds, 2008 was still on the other side of "Peak SEO". This was particularly true for programming information, which tended to live in dense, hard-to-crawl and thus poorly-indexed databases or in some cases (Experts Exchange[3]) actively obfuscated. Google was still leaning heavily on the old DejaNews archive (and Google Groups that had swallowed it) for a lot of more obscure questions, but... had kinda broken all of those in various ways. Stack Overflow's format was very friendly to Google, and Q&A quickly acquired very good ranking, with Google introducing a microformat[4] based on SO's layout for sites willing to present information in this manner.

- ...Reddit was popular, but also kind of a trash fire. Ok, maybe there are a few constants in life. There were good programming communities there, but, uh, not where the unwary would think to look.

- ...There were good, helpful programming communities on IRC too. So I'm told by people I trust. Maybe there was a secret knock or something. Anyway, there were also plenty of the other sort of channel, where asking a question would get you mocked at best or given a script to wipe your harddrive. As crazy as it sounds, a site where you might be brusquely asked to clarify your question and then given a working answer or nothing at all was much nicer than the status quo for an awful lot of folks stumbling around looking for help.

- ...GitHub barely existed. git support on Windows was iffy. Google Code was still a thing, Subversion was king, Mercurial looked like it might be the next king. Normal programmers used pastebin waaaaay too much. Stack Overflow was arguably the most "put together" site at the time.

I wanted to end with that last one, because I think it points out the real answer to your question: Stack Overflow of 2024 is still... Pretty close in terms of what it offers to Stack Overflow in 2008. Meanwhile, GitHub, GitLab, Discord, Slack, Google, even Reddit not to mention thousands of other services (most recently a lot of GenAI-based stuff) have spent the last 16 years trying to outdo each other in various ways with the intent of grabbing the attention and loyalty of programmers / tech-workers.

If I'm running a little project now, I can set up a GitHub repo w/ wiki, forum, online collaboration (including hosted build system) and if I need more a little Discord or Slack server will probably do the job. I can moderate all of that myself, or lock it down, or appoint other folks in roles to moderate. I can pick a license that suits the project, a Code of Conduct that suits its growing community, use Markdown or something similar pretty much everywhere... That's all so far beyond what was available anywhere in 2008, and so much easier and less restrictive than what SO provides...

SO got big because the 'Net was a shit place for programmers. It's shrinking now because the 'Net has gotten so much better that SO looks like shit in comparison[5].

[1]: https://stackoverflow.blog/2008/09/15/then-a-miracle-occurs-...

[2]: https://www.joelonsoftware.com/2008/04/16/stackoverflowcom/

[3]: https://news.ycombinator.com/item?id=3182198

[4]: https://developers.google.com/search/docs/appearance/structu...

[5]: https://news.ycombinator.com/item?id=41371512