You certainly can redirect people to a website/app for a more tailored platform. But it's not the 2000's anymore where sites feature forums, comments sections, and other community features encouraging users to stay in their environment. At best, the ones that remain use middleware liks Disqus or Discord (and that is a whole other tangent that I could rant about all day) or simply encourage users to share on Reddit/TWitter.

They still can, but most sites these days are fine going where the people go, and linking to their custom stuff.