Do you really want to do window management and terminal tasks in your text editor? I'd rather use my window manager for managing windows, or my terminal for doing terminal tasks.
Just try to imagine someone wanting to have the editor fill the entire screen, and designate one small pane to a terminal. I can't imagine how to do that with something like tmux and vim (other than running multiple instances of vim which is bad for its own reasons).
Do you refuse to use vim's tabs and windows for the same reason?
It makes it really easy to write Perl/c, compile and run it, search the history for output of previous runs etc. It's a big improvement on having to have multiple putty sessions, or even alt-tabbing between shells on a box with a UI.
I don’t use it regularly, but it’s handy in a few scenarios. When you’re in a terminal and working with nvim and never launched tmux, it’s handy to be able to build or access a REPL without suspending your editor. Also, in a GUI editor where you don’t have tmux.
