Which leads me to my next point. Using my definition of "illusion of achievement", all gaming is really about this illusion, the difference is only if we accept the illusion or not.
When 'Diablo I' came out, all my friends were playing, and taking there machines over to each others houses to play together. It was this big deal, so I picked up a copy and started playing. I found it pretty engrossing, and played each of the three classes up to wear I beat the game on Hell level.
But then I kept playing. The game was beat and there was nothing more to see or do, but I was still playing to get 'phat l00t' and kill the next mini-boss.
Then I downloaded a trainer for the game. I could give myself any thing I wanted.
I never played the game again. I never even played with my new stuff. The 'illusion of accomplishment' had been destroyed. I realized I wasn't actually doing anything any more. I played through Diablo II once with one character. I couldn't even manage to push myself to go through the game a second time. Unlike Diablo I, Diablo II had lost its dynamic elements. The game had been pared down to its action/reward essentials, and the trainer which let me get whatever I wanted had pushed me to see through that and I couldn't regain that illusion.
I don't have a problem with someone who enjoys Diablo II. I play 5-10 minutes of Bejeweled Blitz almost every night as a way to unwind and decompress. It's basically the same thing; heck, for a participation perspective, it's almost the same game. However, for me, my particular personality quirks gives me a relatively low tolerance for Diablo style games. If I get addicted to some action/reward loop, it tends to be to games where there is a higher illusion of personal skill and less investment in the character skill. Or, to put it in RPG terms, I'm not that particular sort of power gamer who enjoys the thrill of a min/maxed character wading with ease through the opposition with his degenerately powerful optimized build. I'm closer to a puzzle solver, who likes defeating the obstacles irrespective of the numbers on my character sheet.
But I've seen those players. They are the sort of players whose enjoyment of the game not only depends on playing the ubermensch, but having built a character that can defeat anything in a round or two, also cheats on the initiative throw so that they can be sure to be able to do so unhindered. I've met, not one, but several of these players over the years, as well as a few 'Teflon Billy' style gamers who get off on always beating the DM more or less fairly. And before anyone gets sidetracked again, I often enjoy playing with them. Sometimes, it's really nice both as a DM and a player to know that there is this crazy killing machine in the game that can always be counted to get the party out of whatever that's thrown at them. As I said earlier, as a DM I always prefer a mixture of power gamers, roleplayers, goofs, and puzzle solvers at the table because I like 'the whole game' and when one sort of player is missing it tends to leave a hole in the play experience. So this is not about 'roleplayers are better than roll players' or any of that crap.