They're worried that if others control the sector, then they might start building their own advertising platforms (or change the dominant revenue model to somet

They're worried that if others control the sector, then they might start building their own advertising platforms (or change the dominant revenue model to something else entirely) and cut Google out of the game. It's a preemptive strike, primarily against Apple. Bit like Microsoft's costly entrance into the home console market, just to ensure Sony didn't usurp the Windows/PC platform by providing equivalent services via Playstation. Edit: they've probably also boosted their overall revenue in the short term because not everyone can afford an iPhone and the other vendors were so far behind iPhone OS, ads on their platforms weren't worth as much.