Celebrim
Legend
D&D beat out other games because at first it was the only game, and because when other games came out it still out-competed them.
Ultimately, my point - and arguing for or against it - depends on something subjective. It's not possible to prove that one product or the other has superior quality, unless by 'quality' we only mean something very limited like the number of typos or layout issues that it has.
However, I will argue again as I have argued elsewhere, that the 'standard narrative' about why D&D was successful is incorrect. Going 'first' is by no means a huge advantage. Plenty of things hit the market first only to lose out to some other product. VHS beat Beta. IBM's PC's beat out the Mac. Nobody uses Palm Pilots any more. Ultima Online did not become the standard in fantasy MMORPGs. Id doesn't dominate the first person shooter market. More often than not in fact, first to market is a disadvantage. IMO D&D did not succeed because it was first. It succeeded despite being first.
Part of the standard narrative is that D&D succeeded because of the huge amount of negative press that it recieved. Of course, this is also a bit wierd and hard to believe if you think about it. Negative press doesn't usually help a product succeed. I'm deconstructed this myth at great length elsewhere, so I won't go into it again here, but I believe D&D succeeded not because of the negative press but despite it.
Sixteen years ago, I would have bought into the standard narrative myself. I was frustrated with the lack of realism in D&D and the inelegance (as I percieved it) in the clunky 1e game system (or non-system). It's various shortcomings had come to grate on me too much. So I left the system and went exploring, and that brought me some much needed perspective.
I'm now convinced that D&D succeeded on the basis of its many abundant merits (which I've discussed elsewhere). D&D was a success because it got far more right than it got wrong, and the various "fantasy heartbreakers" (as they've been called) and rival gaming systems that appeared almost immediately failed as I had to properly appraise the game. The secret to D&D's success is that the game system had been created not as the result of some untested theorizing about what would make a good game, but organicly as the result of playing the game intensely for years prior to it being published. Because it wasn't relying on theory, but practice, it was playable and approachable in a way that most of its competitors weren't. There is lots of evidence for this, but for me one of the most convincing is that almost without exception, cRPGs have adopted the D&D model of chargen and combat resolution rather than the alternatives, and seldom depart far from it. I am convinced by my time spent with other systems that this is not merely driven by nostalgia or a lack of imagination, but because disparaged concepts like class, levels, and hit points are actually the best systems available for solving common gaming issues.
And Wizards is making adventures. They are making more adventures than anyone. They don't sell them in stores... they give them out for free through Encounters and through LFR and other organized play.
I can't say this without offending someone, but IMO most of these are crap. It's a good thing that they are free, because most of them aren't even worth that much. You'd have to pay me to run most of these for a group. Maybe its not the fault of the writer, but of the format and the mode in which these are created, but they are typically unimaginative combat oriented slap dash which gives me no reason to care about them.