It's also not very good at keeping programs running. It can't survive a reboot, for example. It's possible to do that, and there's stable software that does it. Generally any program that can handle a suspend and resume can handle being persisted across reboots.
Not that I have a great suggestion for alternatives — I'm not really in the market right now. I use i3 for window management (not 100% satisfied, but it's definitely high quality software). I don't often run long-lived processes in ssh sessions these days. When I do, I use tmux, which is fine, I guess, if I don't have to do it often.