Okay, so Mozilla's claim is that....users are so brain dead, they can't figure out how to install other browsers and that Microsoft suggesting Edge to its users, somehow prevents them from doing so?
No, the reason Chrome, Mozilla, and other browsers aren't being used and are losing market share is because they are straight up awful. I jumped ship from Chrome years ago, to the non-chromium Edge, because of how terrible it had gotten and it has only gotten worse.
Firefox has been terrible for even longer, literally well over a decade. I even tried a fork of it called Waterfox, and while slightly better, it still suffered a lot of issues. Nobody uses Firefox because it isn't a viable alternative to anything.
I've worked in IT for two decades and in terms of speed, resource usage, security, and privacy there is nothing that touches Chromium Edge. It is factual and has been proven by independent analysts. The settings can be a bit murky and fiddly but once you tweak everything just right, it is insanely good.
Here's a suggestion Mozilla...make a good product and you will see your market share rise. It's been a long time for you but, if buckle you down, you might just pull it off.