Back in the day before the rise of Facebook, there was an open source service that combined all the popular messaging protocols - MSN, AoL, IRC, etc.
It was called Pidgin[0], and it never got particularly big.
I see the same thing here. While it's interesting, I'm failing to see what the use case is. What's the niche that needs this solved in a big way?
No, it wasn't a "service" - it was a program. Unlike this thing.
The main difference between this and Pidgin seems to be that you pay a monthly fee for someone to man-in-the-middle all your communications.
It is a service, because the bridge is a software that need to be keep operational 24/24h and sometimes this is not so trivial (if I don't get wrong WA need an Android emulator running).
WA works with a pure go-based bridge. No Android required.
The rest of your comment is true though. Keeping these bridges up 24/7 is quite a bit of work. Most people (even technical ones) probably won’t bother with that.
I know because I've used the bridge.
[1] https://github.com/mautrix/whatsapp [2] https://docs.mau.fi/bridges/go/whatsapp/authentication.html