>But if you're making half a billion in revenue every year on top of someone else's tech, you need to stay involved and contribute back in a very significant way.
Where does the GPL state this requirement? It doesn't.
If WordPress doesn't like this, they should have licenced their software under the AGPL or some other licence with stronger copylefting.
Plenty of large commercial entities use BSD licenced software and make a fortune off the software, with little given in return. Take FreeBSD and the significant commercial operations it drives. They never whinge. Because that's the choice they made, and they stick to their principles.