Probably cause most users don't actually care, otherwise Firefox would have more than single digit market share.
You may as well say that moviegoers don't care about art because studios only finance superhero franchise films.
Do they? Do you think the audience drives the genre of movies that are popular or vice versa?
Brave has <1% market share.
I've been daily driving Brave on every machine and device I have for a year or so now... and I really wish they would have just stuck with the "Privacy Focused Chromium" thing. They've wandered far down this path of "lets just add every feature that comes to mind" and it's really not helping it's usefulness.