True. 
Double ratchets is the part of the UX people dislike the most with SIgnal, WhatsApp, etc... 

On Nostr, groups can be so much more than just Chat.
As in, you can have a private group with your wife that also has your calendar, notes, pictures, etc... 
Not having these events accessible from multiple devices or seeing them disappear after X time is incredibly unattractive.

Private relays offer a way for private groups to be as private/secret as the use case requires. 
They can be anywhere (cloud, self-hosted, in the device itself, Tor connection) and have any rules. 
And they can be transparently monetized.