I love emacs. I'm using it every day. But using emacs as a wnidow manager (exwm), browser (eww), or main shell is a crazy idea. The answer is very simple: emacs is single threading and elisp interpreter has own implementation of the tool like Python GIL that protects its own inner state. It is not a problem when you use it as a text editor. But imagine the situation when the process or web page was frozen? It freeze the whole system and only reboot can help.