Not ridiculous at all, depends on your threat model. It's perfect for me.
Can you trust your information stored at your messaging app's servers stay secure forever? Can you trust that company to never get compromised? So yeh, they go through all the hassle of making things "secure" but attach everything to something(phone number) most of us can't get without revealing our actual details. So yeh, its ridiculous to go through all this hassle to make things private and secure, but force people to use something that de-anonymizes everything about them.
I don't write anything that would be interesting to the NSA, I'm not a target for them, so I don't care if they see I use Signal.
BTW, say you have an anonymous Telegram username, I'm pretty sure it's trivial to find your name from the content of your messages. Or just from the metadata.