Not all public communities have government agents in them. The point is also to block passive collection. And to promote good tools for cases when it’s important. For private groups, do not add random people. The thing is that Telegram has a weird history WRT encryption. While Signal has been created by a cryptographer with a great reputation and is maintained by a foundation. But telling people it’s all bad and the same is actually harmful. Do not trust blindly, but make good choices. Do not use Telegram.