>With Telegram I can see at least appeal in using it as news source, chat room or for bots, but what offers Signal besides hype about The Current Thing?...

I use Telegram as a less 'facebooky' alternative to WhatsApp. Most of my friends and all my family are on it and, as a convenient messenger, it has a lot going for it; fast, 100% reliable sync across all my devices, generous file transfers, ability to quickly ping someone your location, ability to set up and subscribe to channels, etc. etc.

It also has some infuriatingly shite 'features' such as the fact that one party in a conversation can delete messages from the other party's device and [as is oft-mentioned] the fact that comms are not E2E encrypted by default. But, on the whole, I reckon it's the best all-round messenger app out there. Just so long as you're not under any illusion that your comms are in any way secure.

I think you are overestimating. I know more Jabber users than Matrix. And the overlap with people I’m in actual contact with, as opposed to people I used to study C.Sc. with, is 0 for both.