Once they get to that temperature, which can happen in a matter of minutes if you are doing something cpu intensive, they throttle the cpu, thus slowing everything down, which is counter productive if you are doing something cpu intensive. They can spread that heat over a larger area, thus heating up the whole device, or they can put in active cooling, or they can put in a cpu that doesn't get that hot. The Atom is a cpu that shouldn't get that hot. It's probably not as fast as the i5, but it can certainly run Chrome and other apps though probably games would suffer.

The issues we see with Surface Pro 3 overheating is where it's not expected to overheat, such as using Chrome. Using IE is fine, but when you use Chrome it overheats. Turns out a lot of the time it's related to ABP (adblock plus). Switching to uBlock seems to resolve most of the overheating of Chrome.