This is only true if you accept an extremely myopic view of storytelling.
A Song of Ice and Fire is about the illegitimacy of the Lannisters' reign, the choice to execute Ned Stark for discovering it, and the ensuing civil wars. Ned Stark isn't a "fake protagonist" because he dies. He's a protagonist and he dies, and then the story continues. Not every story needs to be a Save The Cat Hollywood screenplay to be "correct," and not every character arc needs to be satisfyingly resolved.
You not getting Boss Baby vibes from Martin's writing doesn't mean he's done anything wrong.
A Song of Ice and Fire is about the illegitimacy of the Lannisters' reign, the choice to execute Ned Stark for discovering it, and the ensuing civil wars. Ned Stark isn't a "fake protagonist" because he dies. He's a protagonist and he dies, and then the story continues. Not every story needs to be a Save The Cat Hollywood screenplay to be "correct," and not every character arc needs to be satisfyingly resolved.
You not getting Boss Baby vibes from Martin's writing doesn't mean he's done anything wrong.