Given the remote-first container-based world we're heading towards, decoupling UI (terminal emulator) from its "backend" (tmux, code-server) is a great design decision, which I think will ultimately define what the "next generation" of terminal emulators is. Imagine being able to open tabs directly on remote host, reconnect without losing state, etc, all while using native UI (so Cmd+T to open new tab, Cmd+F to search, etc). Productivity game changer, which currently only the iTerm2 users can fully enjoy.
Ptyxis (putting its backend in running containers), WezTerm (native handling of ssh sessions) and VSCode's terminal (starting a proprietary code-server binary and connecting to its TCP port) have reached some of this functionality, but in their design they need some out-of-band mechanisms to handle the connections, ultimately limiting the scenarios they can handle.
Meanwhile tmux -CC [0] and ht [1] are sending both their control channel and data channel over the opened terminal itself (in-band), making them flexible enough to support any configuration. Something complex like `ssh jumpbox -- ssh prod -- podman exec -it prod /bin/bash -- tmux -CC` should just work, as if everything was running on your local machine.
