people didn't want to pay to maintain the sites, so they sort of died out largely (lots still around but not like it used to be) and many of the users moved to:

people didn't want to pay to maintain the sites, so they sort of died out largely (lots still around but not like it used to be) and many of the users moved to: 1) Reddit 2) Facebook 3) Discord Lots of them just disappeared and never 're-appeared' anywhere, as the interest in paying to maintain them just died out. Personally I prefer reddit to the other 2, as its searchable, but overall the web feels a lot less rich than it did when forums were more popular and niche knowledge seemed more common without onerous reddit/facebook/discord moderating.