This is not entirely true. For example, Calendar.app does the same by locally extracting the .ics out of Mail.app without ever sending anything to Apple.

I don't think Telegram's UX is tied to their permissive privacy, but they do seem to start with UX then do what's needed to support it. That does give them an edge. (Instagram has terrible privacy and actively mines information from chat and their UX is only passably good.)

> This is not entirely true.

My point is that it's generally harder to add those features in a privacy-preserving way. GMail couldn't do it if it couldn't read the content of the emails, period. It doesn't mean that there is no way to have nice features in a privacy-preserving way. I just said it's harder (sometimes impossible).

> I don't think Telegram's UX is tied to their permissive privacy

Not exclusively, but it is obviously a lot easier! Take a web client: if the server has access to the data, your client can just fetch it. If the server doesn't even know about the existence of the group, that's harder. Why do you think only the "secret chats" are E2EE in Telegram (and those don't support groups)?

> then do what's needed to support it

What do they do to support privacy? They don't have E2EE except in the secret chats! That hasn't changed in a decade!

> Instagram has terrible privacy and actively mines information from chat and their UX is only passably good

This keeps getting further from what I said :). Of course, it's possible to do worse than Telegram!