I think it's absolutely correct that, for Google, it doesn't make sense to charge for sync. I also think that anyone who's ever relied on sync knows that there is a lot of value in doing it well - especially in a B2B context. It's true that "just" filesystem sync isn't a full product. The product would probably be sync-as-a-service where you can manage distribution and deduplication of resources across your systems.

So we have a situation where it doesn't make sense for Google to focus on the feature, but the fact that they have the feature at all trips up specialist companies.