Title suggests it’s about gaming PCs. A gaming PC without a graphics card is not a gaming PC. Also if you bought a graphics card separately then you would at least need to open up the PC once to install the card. You will also need to know something about a power supply (which in most pre builts is garbage). So I don’t think this is about regular joe walking in to buy a PC. This is about a gamer Joe trying to buy a PC. And if that gamer Joe has some sense then s/he should opt for a pre built PC that comes with all components or if s/he has the graphics card then go ahead and attempt to build on their own.
Again we are talking opinions here and I find it stupid whereas you find it an intelligent thing to do. That’s ok, we do not need to argue about it.