[Matthias247]

That doesn't really contradict my statement. I agree that the feature is already there in Meteor (only with another query language), and that it's also supportable by RethinkDB, Firebase or any other backend/db which supports subscriptions. By what I meant is that it requires support for subscriptions all along the chain, and this is not supported by legacy REST/GraphQL/etc. APIs. The lack of alternate DDP backends besides the MongoDB one (and of course the creation of custom subscriptions) seems to confirm this.

I am sure they could now update their query language to GraphQL instead of MongoDB queries by adapting and extending the existing system, but I don't know if thats currently the biggest problem for meteor adoption or only something that is nice to have for some GraphQl/Relay fans (which still might be using these directly anyway).