Looks like since this was posted, the page author has closed another 10% of open emacs bugs: https://lars.ingebrigtsen.no/2022/01/20/13x10/
> And that leads to Emacs hanging if the mode’s font-lock rules hasn’t been written in a careful manner, and they mostly haven’t.
No, they mostly haven’t! That applies to so many things :D
I'm pretty sure you can't find any public statements by commercial projects written in the same off-handed spirit :)