(I'm partially utilizing Cunningham's law here) Because all the really security focused apps insist on per-device private keys, so everything has to be re-encr

(I'm partially utilizing Cunningham's law here) Because all the really security focused apps insist on per-device private keys, so everything has to be re-encrypted by everyone per the other users' device. This mitigates key leakage problems to some extent, but also makes the UX as awful as you describe. I don't understand why nobody (to my knowledge) has yet gone the middle route of having a private key per user. Sure, it's a bit less secure, but it's surely better than users preferring to use un(e2e)encrypted options instead?!