Not all notifications go through FCM but all push notifications do as far as I'm aware - which is what the previous comment and the post title are talking about.
It is, in fact, worrying for privacy implications on the one hand and a real monopolizing factor on the other since if you wish to deliver an app which needs to implement such notifications you're using Google's service or constantly drain the user's battery.
There's UnifiedPush which tries to provide an open alternative but so far unfortunately still sees very little adoption.
While I do not doubt this happening, nor it being sexist at its core, I find no mention of it on the linked wikipedia article.
EDIT: Ah, it actually links to a now-defunct british spacecentre article in the original TIL with the following quote:
and there's an '82 NYT article mentioning it here