Yeah YTP is what I think of when I think of YouTube-originated art form. It's sort of like a visual version of the "Paul's Boutique" crazy sampling to make new art.
Absolutely true - it's actually crazy how much of an art form YTP became. (Not sure how popular it is these days?). It was a whole style with its own conventions, memes, etc. And on the surface, it seems really stupid, but there's a lot of creativity and talent that went into those wild videos.
I've always thought people simply copied the style of “Robot Chicken”, “12 oz. Mouse” and other shows of that era because it was considered “HiLaRiOuS!!!!” by some crowd, and did not require complex work in the video editor.
The really crazy thing is that I initially hated Youtube poop for some reason, despite having made several Animutations. Later on I realized how silly that was.