I mean, I used to use them. AIM, and Steam, and Skype, and... shit a few I'm forgetting. That SNAP or whatever it's calling itself is worth billions is just a reminder to me how behind the times the average investor is. Because none of this shit, NONE of it, ever lasts. Your "customers" can switch to another walled off service in about 1 minute without ever going back to the previous one, and from my (and those I know) experience they never will.
It's all an annoying sham. There could, there SHOULD be a way to IM whoever you want, wherever they are, whenever you want, without having to worry about it. But like with email providers the profit margin for that is next to non existent, if it's positive at all. So we'll stick with our infinite round robin of walled off IM gardens, each one replacing the last as time goes on, forever, cause that feels like it should make more money that "ewww" intercompatibility.