What they usually can't do is the more involved stuff, like refactoring, because there is no company who pays people to implement these for emacs/vim.
It's true that funding is important. CIDER has benefited from this system: https://www.clojuriststogether.org/projects/
What they usually can't do is the more involved stuff, like refactoring, because there is no company who pays people to implement these for emacs/vim.