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.
[0] https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta...
[1] https://addons.mozilla.org/en-US/firefox/addon/ublock-origin...