Most people, otoh, enjoy playing games, watching videos, that sort of thing. Some people even do work that's dependent on the graphics card. Just because you use your computer for a very minimal amount of tasks doesn't mean everyone else does.
With my arch/xmonad laptop I can handle everything else, except that damn Witcher 3 :)
Most PC gamers will tell you that the experience usually sucks and is often poorly performant.
There are a million and one ways to use your graphics. Be it watching videos or gaming, which while you might have a problem with that, is actually done by people. It can also be used to smoothly decode and render a training video, or to make spreadsheets more pleasant to crawl through without the screen tearing and making everything look like a mess. There are even more minuscule applications you can do with graphics hardware and the software to drive it: transparency to subconsciously still remember what you're returning to when you click on another window, for example.
As nice of you as it is to warn the parent about their information-action ratio, you could use this opportunity to appreciate people's freedom of choice as well as understand there is more to Windows and Mac than Netflix and Call of Duty.
You're not adding anything to the discussion.