that as the case may be, the same argument applies to vim (i use vim, with at least some of its keyboard shortcut glory, and love it); it might be faster in a lot of cases, but at the end of the day editors like sublime, atom, brackets, etc all have a much larger user base because people aren't willing to learn

You sure about the user base count?

vim is a lot older and's got a lot more time behind it than all the alternatives you mention.

But you're criticizing tmux - which is solely used by power user programmers who are willing to learn.

No, they're criticising tmux as a proffered alternative to a full-featured terminal emulator, which is often used by non-power user programmers who are not willing to learn (like me).