Oh, now I get it. It turns out that General Motors’ decision to pull out from Facebook advertising right before Facebook’s IPO was just a big hissy fit. Ad Age reported this week that GM’s explanation that ads on Facebook were “ineffective” actually came down to this: it wanted to run big, splashy units that are completely out-of-sync with how advertising on Facebook works. And Facebook, knowing this, said it wouldn’t give in. Even though neither GM or Facebook would comment on the Ad Age story, this new, updated report about GM’s pullout has all the signs of being accurate, because it has GM and Facebook comporting themselves in exactly the way you’d figure, given the situation. GM played the role of the deep-pocketed advertiser, who is used to its gargantuan ad budget getting it whatever it wants; Facebook stuck by the precepts outlined in its S1 -- which, if anyone at GM bothered to read it, clearly states that, even as a public company, Facebook would favor user experience over the short-term cash shoveled at it by advertisers that would make its quarterly numbers look better. (I should stop at some point and mention that Facebook does have a big, splashy ad unit, the so-called Logout Experience, which takes over the closing page of Facebook on the off chance that one of its 900 million users should logout. OK, consider that mention done!) Apparently, what GM had in mind was much more intrusive than the Logout Experience. It sounds like it had its collective mind all wrapped up in visions of the kind of ads you see when you log on to nytimes.com, only times traffic numbers nytimes.com can only dream about. What’s completely lost in the discussion is this: that if GM really wanted to annoy people -- including its “Likers” -- the best way to do that was run a big, freakin’ ad on Facebook. Facebook really isn’t built for these kinds of ads, and never will be. It’s not what Facebook wants, and, more importantly, it’s not what users want. Even if Facebook was watching its own interests in declining to give GM bolder ad units, it actually ended up doing GM a huge favor. Still, you have to feel a little sorry for poor GM. This skirmish between one of the world’s biggest advertisers and one of the world’s biggest platforms is really the story of how media has changed -- and for major advertisers, it isn’t for the better. Once able to gather tens of millions of eyeballs at the writing of a check, the GMs of the world now finds themselves in a place where that same check doesn’t buy as many eyeballs. And then along comes Facebook, a gold mine of a property closing in on one billion users, as other audiences shrink. If GM could just do what it has done with previous platforms, the good old days would be back -- even if all Facebook would allow GM to do is advertise to its base of Facebook “Likers” -- who would then, surely, spread the word. But Facebook, as big as it is, is also a symbol of how, as media consumers, we’ve moved on from mass consumption. We may all be spending inordinate amounts of time on it, but our experiences on Facebook are customized, and our tolerance for intrusive advertising on it is low. Facebook knows this. It sounds like GM doesn’t.