because they are making an extra step: instead of the snapshot being actually an object manifest, they store the snapshot metadata in a relation database.
I have a use case where we do 100k changes a second. I bet you "their unlimited snapshots because we are cool and using dbs for metadata" will fail in such a use case.
Every commit in Delta is time travel-able. Defaults in Delta clean up logs in 30 days (and data in 7 days but requires a VACUUM be issued.) You can set those retention periods to any arbitrary time period, but it's typically advised against due to the cost to store all the historical data.
