They all still exist, but we don't have the collective courage to use them when it means you might miss a status update from your friends.

The vast majority of people aren't aware of open versus closed protocols. If enough people they want to communicate with are using it to counterbalance how frustrating it is, they'll use it. It happened because businesses realized there's profit in lock in, and they threw resources at it.

Open protocols are still there and still used, but we're sad because the smaller userbase is frustrating. Just like how people still publish human written content to personal blogs, but they're proportionally non-existent.

Closed platforms have salaried teams of workers and salaried teams of marketers. Often they usually have user friendly support too.

Open-source always has a certain level of "jank" that tends to decimate interest from common folks.

Yeah, there are precisely two apps that can exchange with Whatsapp: one is still in beta, the other is by invite only, and for "professional networking" or something like that. https://news.ycombinator.com/item?id=46746476