The problem here is the ambiguity. Someone who uses the original meaning of comprise will interpret a sentence in the opposite way of someone using the new. "America comprises many states and territories" -> "Many states and territories are comprised of America" have the same meaning with the original definition. With the new definition, you'd have to invert both sentences.

This is called a Janus word because it can be it's own antonym. There are other Janus words, like "table" as in "to table a topic for discussion", which means opposite things in American vs British English. The author touches on the fact that that's a regional distinction, but there is no such regional distinction for comprise. Therefore it makes sense for a website like Wikipedia to pick a single form, and the original is still more widespread than the new.