In my closing on 30-year career in this industry, "managers" have been the least important part of any team, and had the least impact on success or failure. I'm not anti-manager at all (although I have spent my entire career trying to stop people who think they are rewarding me or giving me a promotion by giving me more "manager" duties. I have zero interest in deciding compensation or going to more meetings), it just truly is a position that is the closest to fungible. Everyone fear mongers about AI replacing engineers, but in the real world it could far more easily replace manager level resources.