I miss quite a few things about the Old Internet, and one of them is how easy Pidgin, Trillian, and the like made talking to people on Facebook Messenger, Google Talk, AIM, ICQ, or whatever. I think I even used a social media aggregator at one point so I could stay current on Facebook and Twitter at the same time.
I don't think that's possible anymore. Talking to people cross-platform is definitely not possible without something like Beeper (which is buggy, but not because of Beeper)