You can script the heck out of it. I've got little scripts for opening layouts that I commonly use, like open up SVN view for this and that project, or open up a grid with all my app servers and synchronize the input.
Your whole terminal window becomes "paged", you can scroll up and down with the keyboard at any time, search strings, and so on.
You can copy and paste from window to window and from pane to pane without leaving the keyboard.
If you accidentally close a terminal window, tmux got your back.
Reasons to use even locally with tiling wm: https://m.reddit.com/r/vim/comments/1mhqdw/is_it_worth_it_to_use_tmux_or_scr