Apple's only slightly worse than all the others in that they severely limit what you can use iMessage on, but I'll always be a lot more pissed at them because they kicked off this whole mess.
I really miss the days of when I could load all my accounts into Pidgin (Gaim!) and have almost everything centralized. Now I have a teams window (which doesn't bother me too much since it's a work app), a tab for slack, a tab for the umpteenth iteration of whatever Google has decided to call their chat platform, a tab to get SMS messages through google messenger (a welcome change), a window for signal on the desktop, and tabs for Facebook and LinkedIn (both or which I try to never visit, but would like to know if someone contacts my on, and I refuse to load on my phone). I just realized I've apparently abandoned my ICQ/AIM accounts to the past.
That's the desktop. I have almost all those as separate apps on my phone, with separate ways to use them, separate notification preferences, etc.
The instant messaging ecosystem has gone to complete shit, and I doubt anyone that used it seriously before this happened will disagree. And what we got in exchange for every company walling off their own IM system? Honestly, I'm not sure anything that couldn't be recreated fairly easily in a client with a couple months work if someone had extended their protocol to do more.