The problem with vanguardism isn't that there are people who protect/stand up for others, it's that it inevitably institutionalizes those people into positions of power over those others. Nurses, caregivers, etc. aren't "supposed" to have power over their patients, but they very often do. Humans are already good at protecting and supporting each other--no need to risk creating a power differential by forming a designated vanguard to rigidify it.