tmux does support scrolling and copy-paste, but they often work subtly differently than the way they do in a native terminal. For example, when I try putting `set -g mouse on` in `~/.tmux.conf`, scrolling mostly works fine but if I scroll up and then start typing or press up, I won't jump right to the bottom of the session the way I'm used to in native Alacritty (which I will often do as a way to return after scrolling back through a bunch of print output). This isn't a huge deal, and you can definitely get used to it, but it can be frustrating if you like how your normal terminal emulator works and don't want it to change.