Earlier quoted context omitted.
As a reminder, Telegram groups are not encrypted at all, and 1:1 chats are not encrypted by default, so while WhatsApp might see your contacts, Telegram can see most of your messages.
As a reminder encrypted messages aren't easily searchable -- this is a simple trade off and not some dark pattern default. Many Telegram users are away of it's quirks and how it operates differently to other IMs. Any tool will do damage in the hands of a bad workman. A good way to infer Telegram is reliable is how many despotic tyrants and corrupt countries ban it.
No, this only tells you that it's used en mass in those countries.