That's because he's using search hits as a primary measure of how much services are being used, which (maybe) kind of works for consumer services but doesn't wo

That's because he's using search hits as a primary measure of how much services are being used, which (maybe) kind of works for consumer services but doesn't work at well at all for services used by developers (at the least, they should be judged on their own scale). Which is why you see Cloud Messaging popping up in that list - it's just not something many people talk about, but that doesn't mean it's not heavily used.