Why do processors for laptop computers not require the large heat sink and fan combinations that are used in PCs to dissipate heat?

Simply because Laptops are made to be portable and if we had a heat sink in a laptop it would be about 5 inches this which would look ugly and it does suck because laptops overheat very easy that's why it is so important to clean all the dust from your fan every 2-6 months because dust builds up so fast and if you look at a Computer you will see that usually there is a fan on the heat sink to call down the processor and there is a fan at the front that pulls all cools the hard drives and disc drives ect. and there will be one at the back to help cool down the rest of your pc and you can add more in if you want because the cooler your system the better it will run. Like with most computers we could leave them running for a week and it wouldn't get that hot but with a laptop if we leave it on for about 24 hours it will get really hot and it might shut itself down.