Knockout power comes from technique, core strength, and genetic factors. Strength of the legs is a small factor. Proper technique starts in the legs.
Your trunk i.e. glutes, thighs, hams and midsection are what constitutes your 'core', therefore I am still right. Yes, technique is important, but you have to use your legs to maximize that technique and the bigger the legs, the more power behind the technique.
LOL that is absolutely hilarious if you think GSP or Bendo are choosing not to finish guys. GSP fights safe that's a fact that even he acknowledges. But he also doesn't have finishing power. You will never see him KO a guy with 1 punch the way someone like Hendricks does.
I will give you 1 guy that would support your argument though. That would be Tyson Griffin. He has a few KO's on his resume and massive legs that likely play a large role in that.
But your generalizing statement just isn't true. Especially in the cases of GSP and Bendo.
GSP fights safe. Yes, I have not dismissed that. But imagine if he DIDN'T fight safe? You say he has no finishing power, but excuse me, who finished Matt Hughes with a headkick?? He finished Matt Serra by thrusting his massive legs high into the sky and having them drop on his body, which seemed so painful, that the referee decided to stop the fight.
The fact is, safe or not, his legs give me an advantage in finishing opponents.
Ben Henderson's style is to wear you down until you quite. If he landed a headkick or someone, you think he wouldn't finish them? He wore out Donald Cerrone in the 1st round of their second fight by just digging his knees into Cerrone's skinny legs. That's power right there. They know how to finish, they simply just don't, frustrating as it is.