has been proven to have critical weaknesses
Those are not critical, just some aspects being below some arbitrary expectational values. Also it seems there is still no proofs those vector attacks are being used at all.
Yes it can
They chose to target convenience over max security. Shoving strongest options to every user by default is agaiantt that. Reasons include: no history is being saved in this mode, and the desktop client doesn't support it.
Signal has had group chats for many years now
Just because it was implemented by others doesn't mean it's a way to go for everyone. From what I understand, e2e in group chats means that there is going to be a transaction of keys between all members of the chat on adding any new member, and/or on new message, which excessively increases the burden on clients and servers in case of big active chats.
You can ask telegram to implement that, but you can't blame it for keeping it behind some gates. Telegram got implemented e2e between 2 users before other messengers got it working in any form of group chats.
and use Signal
I'll think about it if they ditch electron.
So if an app doesn't support e2ee all data is being saved in plain text suddenly. You prefer calling telegram shitty because you don't care to actually learn what it uses. So it should be fair for me to call any other client shitty for other nonsense.