As you will know; the primary purpose of laptops are for them to be carried around and used out and about, so they have to be small/light enough to be comfortably carried for long periods of time, and so consequently use a relatively low amount of power to have any chance at a decent runtime on battery. Because of this, they must make sacrifices and compromises when it comes to what calibre of hardware they can use. So for most laptops, gaming at decent resolutions/quality settings is out of the question as they have to use a basic integrated graphics card.