It was already a challenge back in those days. I ran the Nokia N9 for a while, and within a year it went from being amazing at messaging due to its messaging app mixing different XMPP providers in one interface (Google Talk, Facebook Messenger, SMS, etc in a single interface) to everyone in the industry suddenly giving up on that and only supporting in-app messaging.
There were valiant attempts to create open source versions of popular apps, but those efforts were always intentionally sabotaged by those providers.
Anyone still posting there is probably not going to leave. Either way, it’s not like this block was hard to circumvent, you could just log out or use a different browser to see the posts by someone that blocked you, so this doesn’t really change a lot.