You don't have a window manager hosting the terminal window on your host OS? That's the argument being made here, you're already in some kind of tiling or windowed environment, why replicate all of that on the remote?
Because with tmux you can reattach to session from another pc or from a phone and still have the same windows and panes?
because my remote is a server that keeps running while my laptop gets rebooted frequently. i can leave a tmux session running on the server for months...
I ssh in multiple times. If I really needed to, I suppose I could use vnc.