Earlier quoted context omitted.
That is already addressed in the parent comment, "deal with a more frequent risk of getting an update I don't like"
This isn't going to significantly increase the speed at which new features are developed, just the speed at which they're released. The overall risk of you encountering a new feature you don't like won't be higher.
Even if it's just a matter of reading the release notes, having to do that twice as often is a non-zero burden.
Of course there is Firefox ESR but I seem to remember Mozilla's website basically explicitly recommending against it with language along the lines of "This is only for people whose corporate policies require it, don't install it unless you have no other choice."