If it's sold in boxes, it should work well on many machines, otherwise it's going to get bad publicity, but you're right that if it's bundled with machines, it only needs to worry about some hardware (though it still needs to worry about all peripherals).
While they needn't go the Apple route with all-proprietary machines, they neither need to go the Microsoft route and have it run on everything.
Maybe a middle of the road approach is best for this niche of the market.