Right -- big publishers' size and distribution model requires them to focus on outsized wins. Their overhead is too high to take on the many smaller projects they would require to feed their cost structure. Smaller traditional publishers face similar problems, having to make few and careful bets and so often having to sell out to survive.

Valve provides an interesting contrast here: with Steam/GreenLight they run a scaleable distribution channel for large numbers of small indies, taking a percentage without making particular and huge bets. It's like an index fund vs. managed fund, where the latter does intense research into specific options. Often that research in anchored in comparative analysis where someone has proven a juicy market exists (ex: Guitar Hero having a million clones in its wake).