Whether they can be worked on independently is not the criteria that matters (and in point of fact, its a false assertion in this case if they're using the same

Whether they can be worked on independently is not the criteria that matters (and in point of fact, its a false assertion in this case if they're using the same database, as neither can iterate on the schema of the data completely independently of the other). What matters is, can I take this service completely offline and have the other still function? If the share a datastore, then the answer is no.