There is not specific reason I think. But consider that a lot of people live in environments so loud that for a lot of laptops the max fan noise is at best a m

There is not specific reason I think. But consider that a lot of people live in environments so loud that for a lot of laptops the max fan noise is at best a mild nuisance, at least with modern laptops. Also a lot of laptop gaming is done with headphones. Then there is the problem that measuring fan noise is harder to do then measuring performance, for the first you just have to run benchmarks in a "normal" temperate room, for the later you need a consistent not too loud noise environment.