I've had lots of laptops die earlier than anticipated and they haven't been used on anything but a desktop. Playing games runs everything at max, the fan is running at max and the whole thing wears out quicker than if you weren't using it at full throttle all the time. That's a fact. Same with a car, same with anything. Rag the nuts off it and failure will come quicker.
It's not a fact, sounds like the laptops you've used were not designed correctly or were of low quality (no price has little to do with quality of internals).
My desktop has been running at 4.3 ghz on a 1st gen i7 at 200-210watts for the past 2 1/2 years (Multi threading enabled).
I've done folding@home for weeks straight with 0 crashes. I last checked my desktop about 5 months ago, no performance degradation (neither from gate degradation, or power droop), power system regulation is +-1% from original recorded specs. If there was degradation, it's too insignificant.
In any case gaming should not kill your phone unless you are forcing it to stay on despite having shut down or given thermal warnings.
What it can do however is make any defective phone show it's flaws much much faster than normal use can.