Yes, I should have specified that the emphasis is on the use-case of finding and restoring old files.

Yes, a backup tool never deletes by itself, but the standard way of using such tools is that you keep the last n snapshots - this is just delayed sync.

I don't know anything about backup architectures, but is it possible to be more efficient with storage and indexing(for search) if your use-case includes finding files from 5 years ago, but not necessarily recreate the whole filesystem as it was on some date?