Earlier quoted context omitted.
> This person's arguments seem to hold water. Not in the slightest. Categorically, he's using prescriptive arguments, which are bunk. Language evolves, people can use it however they want.
OP discusses this; the language has not really evolved. Certainly there are some dictionaries that acknowledge the newer confusing usage, but always as an alternate. Also consider the "why": does this phrase pop up more and more often due to misunderstandings and copy/paste? Or is it because people actually want to change the meaning of the phrase and are doing it consciously? I don't see any evidence of the latter.…
This is not true at all. Merriam-Webster includes it as its second definition of three [1]. It is not presented as an "alternate" or as confusing or incorrect in any way. To the contrary, there is a usage note at the end emphasizing its validity -- how it is "now somewhat more common in general use".
> I think it's noble to push against inadvertent usage changes that make the language more ambiguous.
But there is nothing ambiguous whatsoever about "is comprised of". Its meaning is crystal clear.
> But why is it any more valid to push the language toward using "comprised of" in this new way
It's not, because they're not "pushing" anything. People are just communicating in the same constructions they've unconsciously absorbed, like they do with most of language. The only people "pushing" are people like this Wikipedia editor, who is trying to impose an exclusionary viewpoint that, for example, the editors of Merriam Webster disagree with.