I'm going to ignore the personal attacks since you seem to want to genuinely learn something. 1) The difference between WezTerm's multiplexing and say tmux, is

I'm going to ignore the personal attacks since you seem to want to genuinely learn something. 1) The difference between WezTerm's multiplexing and say tmux, is that wezterm's multiplexing supports all the same features/bugs/syntax and quirks as WezTerm itself. It does not have to translate between what it gets from an unrelated terminal implementation that it has only the most superficial information about to its own internal representation and back, which is what a multiplexer like tmux has to do. Tomorrow if Wez decides to add a new feature to WezTerm, he can add it to his multiplexer at the same time. Thus, the WezTerm multiplexer is a) much more robust than tmux b) not a drag on the entire ecosystem since nothing other than WezTerm itself depends on it implementing anything. And therefore, unlike tmux, it is not a horrible hack. To put it another way, tty's are sufficiently complex that multiplexing if needed at all, must be done by the terminal emulator, not an unrelated third party sitting in the middle. You say a multiplexer is another terminal inside the first, I say that is precisely the problem. It is an incompatible terminal emulator.