Portability I guess? And you can get some pretty nice integration with vim or emacs if you live in the terminal. In fact, it’s probably easier to write a few bash functions to dispatch a command to a new pane than it is to tailor a solution to every OS you might use.

iterm’s Tmux setup is fantastic but if you’re switching between Linux and mac and WSL and want a consistent environment, then you’ve got a good reason to set up Tmux to your liking.