And it infuriates me to no end. It's one thing to trust them and their servers and it's another thing altogether to send actual plaintext data around the net, that's crazy and it's what people are implying.
For the record, until WhatsApp implemented e2e their messages were indeed fucking plaintext, and it took a while before they were pressured into e2e. It helps for them that their platform is very mobile based vs telegram, where the service is more server based. Telegram did have enough time to implement a server based e2e 0 knowledge encryption protocol though, it's not really rocket science at this point.