[daurnimator]

  - server-side searching of messages becomes impossible; this essentially breaks message search for most people
  - depending on how it's done, it can mean the loss of messages when changing devices (one of the top complaints I hear about signal)

[coolspot]

They could start with something like Telegram’s “secret chats”, where users explicitly start e2ee conversations separate from regular conversations.

[wwtrv]

They already have secret chats which are supposedly encrypted.