I totally 100% agree with you brother man.
I've always thought of rodeos as being essentially a 45 degree off-axis backflip with a spin (differing from a d-spin in that a d-spin is a straight up and down backflip spin). I always thought rodeos were kind of the exact opposite rotation of a misty.
It almost seems like the term "rodeo" has a completely new definition. Particularly when the spin is 900 and up, I think what people call rodeos actually look like bios. McChesney and Walker are good examples...where they are essentially doing off axis spins leaned towards the landing (or downhill). I think people call them rodeos because the bio looking tricks seemingly now called rodeos, are thrown by popping, dropping the shoulder, and rolling onto the back. It seems like more and more, people aren't going fully inverted on "rodeos", though, this seems less true when doing rodeo 5s. In my opinion, rodeo 5s look completely different than any other rodeos (I know that sounds like stating the obvious, but I mean in terms of the axis).
Flat spins are totally different, though some rodeos can look flattish depending on the grab and degree (or lack thereof) inversion. BUT, a flatspin should look like the skier is laying parallel to the ground and doing a back flip basically. That's not how it's thrown, but if you think about it, that's what it looks like. A good way to think of it would be to imagine running towards a firemen's poll, grabbing it with both hands while jumping so that you swing around it while your legs are out to the side and your body is perfectly parallel to the ground.