I agree with OP that the tone is needlessly negative, but while some people are super into TST, most of us don't care about it at all. I wouldn't say that any given article on Firefox "should" mention TST, because odds are the author won't be in the group that cares.
In an article talking about the pros and cons of Chrome and FF, it would make sense to mention cult favorites like TST. I'm not sure where you get the notion that "most of us don't care about it at all" — perhaps you have more inside info than the rest of us?
Regardless, I don't care about profiles or any of this other stuff, but I don't begrudge the author for mentioning things that aren't up my alley. In my mind, when I read a list-based article, I don't expect everything to be relevant to me.
I'm not saying I would begrudge the author for mentioning TST, I'm saying that they're not obliged to mention things that they don't personally care about. I don't mind if a list of someone's favorite features has features I don't care about, nor do I mind if they neglect to mention features that I do care about.
As for my information, I'm comparing the install base for TST with that of uBlock Origin (both only counting Firefox). It's not a perfect measurement, since not all Firefox users have uBO either, but it should if anything overestimate TST's relative popularity.
Tree-style tabs [0] has 163,716 users.
uBlock Origin [1] has 6,175,439 users (only counting Firefox).
That places TST at about 2% of the install base of uBO, which is plenty small to justify my saying that most Firefox users (and prospective users) don't care about TST.
