There's many of these out there. Offshoots of Wankel rotors that are a disk that wobbles through different combustion chambers, or have more than three lobes... there's quite a few designs, and none of them ever seem to gain any traction in the market. They all have enormous RPM's, horsepower, torque or whatever too.
I'm guessing that there's some severe drawbacks that aren't immediately obvious, or various industries would be all over them. Probably the ability to repair or refurb/rebuild them as compared to a traditional piston engine is a PITA for starters. Or as you noted, the output figures are direct-drive on the shaft, and once you gear them down to something more useful, most of the benefits are lost.
Pop-Sci, or Pop-Mechanics will run a story on one now and then, and... crickets.
They have some niche applications maybe. I think some torpedoes use a kind of non-cylinder high-RPM wobble or rotor type internal combustion engine, probably with nasty stuff like hydrogen peroxide, or hydrazine etc.
Paging birdman...
