This is not for you or Google to decide.
And no, I can sync changes without having to tarball.
I might only touch one of those 5M files a week actually, depending on my structure.
But again, if you ever want to retrieve all 5M files, I hope you're willing to wait a few weeks-to-months, because that's what it's going to take...
Which is why it's a terrible idea not to tarball them first to something more manageable in terms of latency per file operation.