I can more than relate here.
I "suffer" from Asperger's Syndrome, for which I'll leave a brief excerpt of the relevant part here:
"People with Asperger syndrome often display behavior, interests, and activities that are restricted and repetitive and are sometimes abnormally intense or focused. They may stick to inflexible routines, move in stereotyped and repetitive ways, or preoccupy themselves with parts of objects.[19]"
The above passage describes pretty accurately my gaming habits - as a short outline my games have to be in alphabetical order (and other media, but anything without a label I don't care about), I have to complete games (which is why the invention of achievements, a laughable term in itself, was both the best and worst thing to ever happen for my gaming career) and would be capable of extended stints on games that bored the hell out of me.
Which is why my preferred genre is/was the RPG.
I'll use one game as an example: Final Fantasy VIII. It was unpopular in the series so I made it my main game, to be an outrunner and not conform (I realise now).
I've easily completed the game plus 20 times, each time to the best of its ability - maximum of every item, perfect stats (even to the extent of killing 666 enemies with Seifer just so the later obtained battle meter would state that number, as I felt it apt to mirror his personality) and could recite to you parts of the script if you gave me a trigger point.
Was this fun? Hell no, but the idea of it was enjoyable. I had an obsession with lists, writing and re-writing things to do, things I wanted and things that really didn't matter. These things weren't fun either, but the idea of them was.
Where I'm trying to get to, is where I used to be pretty extreme (I have since stabilised and barely play games thanks to seeking professional advice turning me into a much more rounded individual) I see echoes of my behaviours in the gaming populace.
People constantly complain how poor Call of Duty: Modern Warfare 2 is, yet religiously play it. Condemn games before they've even arrived (Left 4 Dead 2) and are first in line to buy them.
Not enjoying the games, but merely enjoying the idea of them. Feelings misplaced by the security of habit. If people were to take an inside look maybe they'd see something completely different to what they expected.
Ever since I did I've conquered a lot of barriers, and whilst games have helped me through some very troubled patches, they also put a ceiling on my progression. The general impression of which I got from this article.