i don't see the point of adding vi input mode to the emulator when we have it inside bash with `set -o vi`
Many interpreters don’t use Readline (e.g. IPython and Zsh), and enabling inconsistent Vi keybinsings in each one can be a bit annoying. From that perspective, adding it to the terminal seems a possibly easier way to get it “everywhere”?
Possibly more universal, but there are also tools like rlwrap [1] that adds readline support to programs that don't have it. From the docs apparently the readline library ships a similar tool ootb nowadays but I haven't tried that and just noticed now when I wanted to share the rlwrap link.