[pvg]

That ship sailed so long ago, fussing over it seems like futile pedantry. Webster seems to have the right idea calling it an idiom.

Take a look these - there's 'comprised of' in the New York Times in the 1860s:

https://query.nytimes.com/search/sitesearch/?action=click&co...

Edit: Something a bit more recent - a 4600 word profile of Charlie Brooker in the New Yorker in which a sentence begins with 'Comprised of':

https://www.newyorker.com/magazine/2016/11/28/the-speculativ...