Mark Ruffalo revealed in a new op-ed for The New York Times co-written with American Economic Liberties Project research director Matt Stoller that many Hollywood stars declined to sign the recent open letter that’s fighting to block the Paramount – Warner Bros . merger. “The most revealing thing about that letter wasn’t the people who signed. It was the people who didn’t. Not because they disagreed — because they were afraid,” Ruffalo and Stoller write. “There are many reasons to block this deal, but we now believe the most fundamental one is what we encountered when asking artists to use their voices: fear. A deep, ugly and pervasive fear of speaking out.” Popular on Variety The open letter started circulating in April and has since amassed more than 4,000 signatures from Hollywood talent, including high-profile actors such as Florence Pugh, Pedro Pascal and Edward Norton and acclaimed directors like Yorgos Lanthimos, Sofia Coppola and Denis Villeneuve, among others.…