Well sure, that's why Siri is going to hold an advantage with iCloud users (if Apple can catch up), and Microsoft will have an advantage with Office users. Those are the three major ecosystems.
A slight advantage, sure, but apple is trapped by the same thing. Neither of their products actually required full buy in of the ecosystem to exploit until now. It was just nice (eg airpods have a nicer pairing experience than other bluetooth devices—infuriating, but ultimately ignorable)