You touch on it, but I think the reason the deletionists won out was that Wikia was Jimmy Wales' for-profit alternative, and Jimmy Wales was the Nexus of soft power on Wikipedia.

He didn't have to tell anyone "Get as much stuff out of Wikipedia as possible so I can make money off it", that was just going to happen institutionally as a result of his clout and conflict of interest. People would obey in advance, and people without enough radar to realize they should would lose out against those who did.