Proof that upper body weight has next to nothing to do with vertical. There are certain upper body lifts that can help, but when it comes to vertical, you want to have the best strength to to weight ratio you can possibly have. 300 pound guy squatting 600 < 160 pound guy squatting 400
I get what you mean... but it's not weight, it's strength, and it only applies to certain areas that are useful for vertical (mainly your core). If all you did was Yoga and Plyos... you'd be a very gifted leaper. Probably a 1 leg leaper, but a leaper. the guys you are showing are great 2 leg leapers and that's because they have more upper body weight and have trained their body to be more strength based through squats and other weight lifting exercises (and possibly other things as well such as Nate being a football player where 2 foot jumping is pretty much the only way you are going to jump in football.)
As for your argument about upper body weight on first... I don't agree with that. If you're goal is to be a great leaper, then you aren't looking to put on much upper body weight... I mean I honestly wouldn't do a thing for upper body beside core work and olympic lifts(which is lower body but includes some upper body)... that's it... and whatever upper body weight I put on would come only from that and other lower body lifts that put on a little weight up top naturally (mostly in core, other areas of the back, and a little on arms/shoulders from gripping bars).
Most people's goals aren't solely to be a great leaper tho. Dwight is a big and having some extra weight up top (all muscle) benefits him on the block. He would jump even higher if he lost some of that upper body weight tho. He is listed as 265 and he's not even 6'10 without shoes. Kevin Durant is about as tall and get's just as high as Dwight off one leg (or damn close) and he's about 200 pounds. The real question is like I said earlier tho is... what kind of leaper do you want to be? What kind of athlete do you want to be? To do you want fly down the court and leap off 1 leg like KD and Lebron? Or do you want more power and the ability to snag boards and dunk from a standstill? That's really the real question.