I now agree with your point that it's not really e2e encrypted, because they never claim they don't have the key.
But I don't think "can't decrypt it" is necessarily a requirement for e2e encryption. Maybe can't decrypt it with a passive attack. With an active attack it's possible to decrypt even e2e encrypted stuff assuming there's no out of band key exchange. Most Zoom users won't bother with an out of band key exchange.