Folks were bitching about the Yankee payroll long before the YES Network came along.
Besides, what is to keep Boston from doing the same thing? Surely the faithful would shell out for the games.
The Yankees are operating at close to a $100 million higher revenue base than the Sox with YES than what NESN can command. The locals will not let them build a new stadium anywhere around the city and moving to the burbs takes away the ability for people to walk or take the transit system to the games. (Move the Yankees to Westchester County and see how that one goes over). The Sox charge the highest ticket prices in baseball which has made the stands packed with rich folk and corporate types.