I used to volunteer my time to a very major forum software. Tapatalk at the time had a very strange business model of having a plug-in/add-on that was free to the forum owner but charged for the app that the end user used. This was, even at the time, traditionally backwards from the current user interaction model: path of least resistance to engagement. It was unpopular among forum admins as they would rather buy a license for it like you would with vBulletin, Xenforo, Invision Power Board - including the people who ran open source ones like phpBB, SMF, et al.

While I understand Tapatalk have changed their business model since then, the damage was already done as the Facebook started to wholesale eat forums’ lunch as far as userbase. The biggest problem is that we never turned forum interactions into a protocol like we did with at the application level (smtp/pop, http, irc, xmpp) or on top of http like RSS, podcasts, or just plain, standardized REST APIs. This could have enabled multiple clients (like browsers) to appear and may have prevented facebooks swift dominance with online communities.

Everyone wanted to own their forum’s experience, but this stubbornness caused the fiction for users to sign up to be greater and greater. Platforms like Disqus attempted to solve this by creating an embeddable service to just drop comments in a context like a blog post, but this ultimately gave users almost no value it they were just in a shouting match against bots with generic messages laden with spam.

Facebook unified the experience for users, where the user could, with an account+app that they already had, browse and join groups and engage in discussions and become apart of communities in a way that forums could not possibly compete with.