He misspoke. Instead of "if you want people to buy a game, just make a good game", I believe what he should have said was "if you want people to buy a game, start a long-running series that slowly grows a dedicated fan base by having each successive title becoming larger and utilizing more marketing, until the series has such a large fan base it can't possibly fail". Goddamn, Skyrim is not some mystical dark horse that exploded onto the scene and surprised everyone. It didn't "beat the market without being the market" because IT ALREADY WAS A PORTION OF THE MARKET. Games with multiplayer or shooter games like CoD and BF3 command a large portion of the video game market because they appeal to people who don't like locking themselves away on a game for 50+ hours. The audience for these games is so wide because it appeals to a wider base. But it will never be THE market because there'll always be the RPGers, the RTSers, and everything in between that'll clamor for more specialized games.
Look at the sales figures for it's predecessor. Oblivion took around six months to sell 3 million copies, but it didn't release a PS3 version until a year later. It's hard to tell what those figures would look like had a PS3 version been released at the same time, but a comparable equation is not what we're looking for. We looking at the fact that at least 3 million people played essentially the same game. If we assume that a great majority of those 3 million were such fans that they decided they were going to buy Skyrim when that came out, (remember we're not even counting the number of people that picked up the game in the last three other years between the two games or the PS3 customers that were included in 2007), then the fact that the game sold that many in the opening days isn't so remarkable.
TL;DR: Resounding sales figures for Skyrim is just the slow culmination of almost a decade of a growing fan base. This is not a new or original game that spat in the face of industry standards. In fact, congratulations RPGers, you've essentially become the CoD fanboys you despise so much, since this game is pretty much the RPG version of Modern Warfare 2.