Not only that, the accuracy of SR missiles and artillery is suspect in high altitude areas in the rarefied atmosphere.
Secondly, the Chinese have vulnerable bridges and choke points along their lines of communication. Once destroyed/disrupted, they have absolutely no way to reinforce their troops and failure of logistics support will spell disaster. Imagine a couple of Chinese divisions deployed on the mountains without supplies. One div needs approx 40 tons of supplies per day including rations, water, ammo, spares and so on. Without this they will be sitting ducks after the third day - like up shit creek without a paddle. Air transport support would need a favourable air situation over the are which is impossible.
So it's no point just firing off missiles and arty without follow up. You need boots on the ground to capture and hold territory.
The Chinese keep mentioning that in 1962 they withdrew as they just 'wanted to teach a lesson to India' is a load of bull! Who withdraws after losing so many troops and spending millions? To cut a long story short, they withdrew because their logistics collapsed. Chinese troops were dying due to starvation, dehydration and disease. But that story for another thread. Or read, 'The snow Of The Himalayas' a true account of the 62 war authored by two Chinese military historians or extracts of the Henderson Brooks report leaked by Neville Maxwell in March 2014.