There's a number of people who effectively use tmux as their window manager - one terminal window doing literally everything. Locally as well as remotely, but it's more... understandable for remote, where other options are often worse or nonexistent.

For them, there's as much variety of desires as for any other window manager, and there are tons of those. But terminal ones are usually significantly easier to configure in wild ways due to having fewer (but more powerful) knobs to tweak, so a fair number choose just one and configure the heck out of it.

My terminal (terminator) does (2) and the "easy" scrollback on tmux messes up the ability to scroll with the mouse, at least with default settings. I just tried it in zellij and that doesn't. Since I'm only using a multiplexor for (3) and zellij does that too, I'm already inclined to switch.

I know I'd get used to them, but the key combos used by tmux seem very odd choices, even to someone who used to code on a real glass tty!