Neovim came along but majority who use vim still use vim. They won't change. This is in a situation where neovim is ahead of vim in certain areas (some may not like it and call it bloat but I call them features).

Unless remacs gives a clear advantage over emacs in terms of performance while still retaining compatibility people won't switch easily. Even then the switch should be quick and painless. (Neovim had those and so some people jumped ship).