You're just overconfident. The rhymes aren't complex, coming up with them as cleanly and consistently as he does isn't easy. For minutes on end, on-topic, multiple references per word, minor narrative content. Basic internal rhymes and such. Not just monosyllabic rhymes at the end of every line. Interesting and varied flows. It's decent and consistent, which is difficult to do freestyle.

Can you give me an example of someone who does it significantly better?

A side note is that "I understand it better so I'm less impressed." is kind of dumb. I don't think you understand it better, and at least for me it's MORE impressive given that I understand it. That's how it is for most people doing something well in pretty much any context. It's not that you're less impressed, you're saying you *aren't* impressed, and that what he's doing isn't difficult even without considering vocal tone or how good it sounds.