That's sort of true, but OTOH vi, Emacs and even Notepad++ can write code and view huge log files. People who are holding out on Atom because of speed maybe don't want two tools where one will do, which is perfectly reasonable.
Even emacs completely shits the bed when it comes to long lines. I love it, but there are things about every tool that requires tradeoffs. I'm willing to deal with bad performance due to decades old technological decisions, in order to gain (to me) unparalleled editing and customization.