on her blockbuster Eras Tour, then blame it on the Boss.According to no less than Paul McCartney, Bruce Springsteen is responsible for this concert season’s trend of marathon shows — stretching three hours and beyond — put on by everyone from Swift and Beyoncé to the “Born to Run” rocker himself.“I blame Bruce Springsteen,” McCartney, 80, joked about the New Jersey legend’s famously epic-length concerts, during a talk with Conan O’Brien at NYC’s Tribeca Performing Arts Center on Thursday night. “I told him so.