I'm bias as can be, but grappling is way more complex than striking IMO.... in the context of MMA anyway. You see a lot more grapplers pick up striking than the other way around.
I've never done traditional muay thai, so I can't say with any true expertise how complex it is in and of itself. I assume, like anything worth practicing, you could do it for a lifetime and never come close to learning everything there is to know.
Sig credit: MC
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