Not really. If you don't care for the PC as a developer you take the money from AMD or nVidia and run away with it. Better to get $10, $20, or $30 millions in one payment instead of waiting that people buy your products.
That makes no sense.
1) If you don't care to be a PC developer, chances are your game will run like a dog and in general will be crap. Then people will be so dissatisfied with your game, they will constantly complain on your forum and your firm will get poor reputation as a game developer with constant bugs/glitches/performance problems.
2) If your game is horribly optimized, a lot of people will decide not to buy it until faster hardware is available. Then instead of buying your game at launch for $40-50, people will wait until it drops to $5-10 to buy it they know you need a GTX780 to run it at 1680x1050.
3) Over time the developers will give access to AMD/NV even if the game is TWIMTPB or GE. Working together just gives each GPU maker with exclusive access in the beginning to better cater the drivers for their architecture giving them a head start. Also, they developers may expose certain feature set that benefits that GPU maker (TXAA option, PhysX, DirectCompute/Global Illumination, etc.)
Developers and AMD/NV work together to provide a more optimal gaming experience to gamers from day one. Both parties benefit. The difference is NV has been doing this for years and years and AMD has only recently started to get serious about it. As a result, we are going to see more and more games that run faster on NV cards and others that take advantage of GCN and unless a gamer can easily afford $1000 GPU setups, it'll come down to the type of games the person plays.
No one is stopping AMD/NV from developing a stronger GPU architecture that leverages OpenCL, DirectCompute, Tessellation, HDAO, etc. The feature that keeps fragmenting the industry is PhysX. If Maxwell is a modern DirectCompute architecture, it could easily trump AMD's best card in all the next gen games even if they are optimized for AMD.