Like look, I could get it if it was "well we're not making money from sales there anyways, so we'll take what extra resources we can get". I'd get that. From a revenue standpoint, that makes some sense, at least.
Implying that having your game prominently advertised on the platform the majority of sales will be on won't matter, but "Xbox Billboards" will drive games more? That makes ZERO sense. Nil. Especially when PlayStation was also putting up billboards and putting out TV spots, to say nothing of paying for half the marketing AND providing development support?
I'm not one for conspiracy theories, but this reeks of either a fundamental misread of the market, or... planted info.