Playing a devil's advocate. Suppose somebody made a clean-room implementation of a MongoDB driver that contacts MongoDB, then passes the data to a MongoDB-compatible interface that shares no code with MongoDB. This wrapper is duly shared. Can that guy then offer a SaaS MongoDB-compatible DB by exposing this driver, connected to a real MongoDB, without a commercial license?

As we notice, all that SSPL would require to share is shared in this case.

Then a wholly-owned subsidiary could build various value-added services on top of that MongoDB-compatible thing without a commercial license. This of course would fail if the wrapper would need to be licensed under SSPL, too.