Telegram group chats are NOT end to end encrypted. Telegram has an option for e2ee chats but they won’t sync across devices, last I checked, ans nobody uses them.
My use-case is E2E encrypted (team) chat coupled with identity verification. In some projects having assurances that you're talking to who you think you're talking to can be a big deal.
Keybase has an amazing, user friendly e2ee story.