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? [0] https://www.pidgin.im/
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.
All Matrix homeservers and bridges are open source. I self host some of them myself. Have been doing that long before Element One was a thing.