That's not always true. Everytime their is a major OS switch you have games that stop working and some can be modified as a work around some can't. With windows 9x to nt systems I can think of south park's shooter not working. Going from xp to vista/7 also dropped some comparability. Keeping an old pc around to play them is the same as keeping an old console and for a while at least virtual pc software wouldn't run the stuff fast enough(although it would now).
I know a few people without TV's but I agree with your point. The console will run off a computer monitor fine. For a few years I had my xbox hooked up to my second 22inch lcd at my desk. The TV shouldn't have been on the quote. In the end it doesn't matter. The guy who wrote the article comes off as an idiot.
Yea a lot of newer consoles can be hooked up to a monitor, but then you have demographics that due to space like dorm rooms people just buy LCD TVs with tuners in them and hook them up to a PC/gaming console anyways.
Here is the problem. It is hard to say you can game on a PC on the couch without using a controller because posture problems as well as the awkwardness of trying to use a mouse and keyboard on your lap.
Also setting up a desk does nothing because you will be leaning forward just to use the mouse and keyboard which puts a ton of strain on your lower back.
Therefore if you game on the PC in your family room you almost need an upright chair and desk.
Likewise if you console game on a PC desk/monitor you are always confined to the small space in your office.
This is one of the advantages of PC gaming. Easy set up, easy to use in a comfortable environment and a social experience when friends come over.