I guess, because taller mountains need a bigger/heavier base (Mnt Everest is only a few km over it's base, stone is too brittle) and a too heavy base gets "liquid" on, or literally under the plate (it's magma underneath).

Only guessing though.

But then there's Himalaya and the whole mongolian ranges on the same plate...

Seeing it like that, we are beings of energy, existing on the thin skin of a ball of molten stone, revolving around a ball of fire.

Its indirectly gravity. The taller the mountain, the more eroding force can be pleced on it. Water travels faster and therefore cuts deeper.

Everest is still uplifting fairly quickly at 1mm a year, but its also eroding at roughly the same pace and won't get significantly taller than it is now. The same is true for the rest of the Himalaya as well, the whole range is eroding at a very high pace.

The Himalaya are home to some very spectacular canyons, including the largest canyon above water. The geology there is on full display and incredible.

Plate tectonics and isostasy: Ocean ridges can only push so much and the denser a mountain range is, the higher the stress on the crust and mantle material.

https://www.youtube.com/watch?v=3rk2jx3eRDE

I guess this only explains the positive constraints of orogenesis.