Imagine spending 1000 pounds or more on a product without any real guarantee that it will work for your intended use of it. So I presume you wouldn't want to do that, but if you want to run Linux on a laptop that's the risk you have to take. There are number of integrated features on laptops that mean a particular model may not work fully with Linux, such as wireless interfaces, 3D graphics, power management etc. For desktop Linux it's a case of doing you research, finding out what works and picking the right components or buying from a vendor that sells Linux systems such as DNUK or Armari. Unfortunately for laptops that is made almost impossible by the fact that laptops come as a complete unit without interchangeable parts and none of the vendors of laptops offer Linux or support. This leaves it down to the customer to work all this out before buying, often with incomplete information about the system's components. So, consider this, if two vendors sold essentially the same laptop at the same price but one offered a dual boot option Linux+Windows, which one of them do you think would sell more units?