Because its MMA not kickboxing.
Uhm, ok. Let me rephrase the question for you, to help you understand;
Why does it work in kickboxing, but not MMA?
You haven't been watching Machida's moves that closely...
He uses sweeps a lot.
Yes, I have. But let me illustrate why your answer isn't very smart; if I ask why shotokan karate isn't used much in MMA, and you say "Machida does it", you fail completely, because you've only managed to find a single fighter as an example. You see, if you'd been able to name 30 UFC fighters who use leg sweeps as part of combinations, you'd seem more educated. Instead, you chose to pretend you're the only one on Sherdog who's studied how Machida fights.
I assume you meant well.
TS doesn't mean leg sweeps used as takedowns like in those Machida gifs. He means leg sweeps used to throw off their balance like what Machida did to Rashad a few times, and like what you frequently see in traditional WKF style point fighting.
Correct, sir. Well, since you understood what I meant but didn't have an answer, I'll just assume it's a difficult question. I wonder if it's just one of those techniques that, while effective, haven't made it into the MMA arsenal yet.
Because it's a karate thing, that's why you don't see it often outside of a Machida fight.
Except it's not strictly a karate thing though. I guess it came to kickboxing through karate, but since it's made it to kickboxing, you'd think it make it to MMA as well. MMA fighters tend to be familiar with kickboxing, after all.
