You're missing the point. Beeper is not a messaging service. It is a service that allows them to interconnect. How many messaging apps do you have? I manage four and I hate it. This tools puts them all in one interface.Not really, because the smallest denominator is... small. We had that already with iMessage falling back to text. Despite that (or because of that), nobody outside the US is using it. Can it do voice/video calls? Voice chat rooms, screen sharing/recording? Can it do bot interactions, chat channels, channel/group moderation & signup protocols? How does it share live location with someone on iMessage? It may be a nice service for some people who are prepared to shell out money for iMessage bubble color. But the bigger problems like Whatsapp privacy cannot be addressed by a bridge. For the masses it is not appealing in any way.
It does not compete with Telegram, Signal, or iMessage. It simply allows an iMessage user or signal user to talk to a Telegram user or FB user or whatever platform. All the customers of those platforms are potentially Beeper customers.
That is why it is innovative. It is a different product unifying the mess all theses messaging services have created. How many messaging services do you deal with? Wouldn't it be nice to have one client that manages all your messages?
There is a catch, and that is that the open source Matrix server does not do video chat for all services yet. Video requires potentially reencoding the stream as each service uses different formats and compression. So that is spotty between services.