StackOverflow was great because it's not like a support forum or a mailing list. It's more like a repository of knowledge. It's been extremely helpful to me when arriving from Google, and I've gotten a couple useful responses to my own questions either. Awesome resource.
Where SO started failing in my opinion is when the "no duplicate questions" rule started to be interpreted as "it's a duplicate if the same or very similar question has ever been answered on the site". That caused too many questions to have outdated answers as the tech changes, best practices change and so on. C# questions have answers that were current for .NET Core 1.0 and should be modified. I have little webdev experience but I know JS has changed rapidly and significantly, so 2012 answers to JS questions are likely not good now.
Where SO started failing in my opinion is when the "no duplicate questions" rule started to be interpreted as "it's a duplicate if the same or very similar question has ever been answered on the site". That caused too many questions to have outdated answers as the tech changes, best practices change and so on. C# questions have answers that were current for .NET Core 1.0 and should be modified. I have little webdev experience but I know JS has changed rapidly and significantly, so 2012 answers to JS questions are likely not good now.