[the_mitsuhiko]

A NAT does not stop you if you do it right. Console games have been hosting servers through NATs for the last decade.

[TheLoneWolfling]

As I said: it gets "fun", especially if you want to do it without a third server to set up the connection. Still doable, just "fun".

[tacotime]

I would speculate that the massive advertising revenue generated by the 'bay probably renders any such 'fun' factor trivial.