I don't know any GUI that beats tmux work portability.

Of course everything depends on exact nature of the work, but personally I would gladly leave text based interfaces behind, it's just that there's nothing better.

I know UNIX since being introduced to it via Xenix in 1992 thereabouts, and never found a use for tmux.

More so, I use the terminal as strictly necessary and nothing more.

9front/plan9 leaves tmux and the like as toys. The moment you can use system tools, 9p and files on everything (even the text of the editor itself) you wont be back to these unusable teletype emulators, be XTerm clones or terminal multiplexors.