Because it introduces latency.
Higher framerates only in part improve the experience due to looking better, they also make the game feel faster because what you input is reflected in-game that fraction of a second sooner.
Increasing framerate while incurring higher latency might look nicer for an onlooker, but it generally feels a lot worse to actually play.
I don’t remember what program it was but I once went to configure something, and the command to “open settings” essentially just opened a text file in vim.
Being a nano scrub that took me a second to get out of.