Telegram only provides e2e encryption for one-to-one conversations and only if you specifically create a "secret chat" largely because of usability and discover

Telegram only provides e2e encryption for one-to-one conversations and only if you specifically create a "secret chat" largely because of usability and discoverability reasons with regard to their major point of focus. Its probably better discussed in comparison to other services like IRC, Matrix, Discord, or Slack that concentrate on feature rich group chat implementation with easy discoverability, organization, and mobility for which encryption either does not exist or is an opt-in or bolt-on feature. Services like Signal, Whatsapp, Keybase, or iMessage that provide e2e encryption for all chats, group or otherwise, (albeit with differing levels of implementation security) have chosen to do so at the expense of things like mobility of chat history across devices and the ability to easily discover and join new group chats and instead focus on a less organized, more ad-hoc form of messaging that's a rather different use case than Telegram's.