Tmux can do a lot of fancy things like “tiling” but the main point is to start a session. You can then detach from it and close your terminal, even log out and log back in and then re-attach to it. That’s generally the purpose of tmux/. It’s just a a way better bsd licensed version of GNU screen.
Not really for me either. I pretty much stopped using tmux when I started using i3 by default. Creating a container served the same purpose; I never made use of the session/detatch/attach features. And kitty terminal has multiplexing built in.
Unless you can make use of a tmux session and utilize the attach/detach features, you don’t really have a need for it.