The two most important electronic marketplaces for games today are probably Steam and the iOS App Store (not necessarily in that order).

Neither of these is as wide-open as the first-gen consoles were. Despite this, both are absolutely flooded with crap, to the point where the most common complaint I see from developers about both is how easy it is for a good game to get lost in the noise — if Valve/Apple don’t feature your title on the store’s home page, you basically have no hope of being found.

So I do think this is a valid concern, though perhaps not quite so dire a threat as the platform owners think it is.