I said semblance of accountability for a reason. Still, Supreme Court justices are appointed in limited number by elected politicians - who have to justify the appointment based on their supposed professional credentials - to discharge a specific set of duties

They certainly would not be more accountable if their appointments were more aristocratic in character (i.e. they inherited them from their ancestors who had been appointed for arbitrary reasons by an unelected monarch) and, like aristocrats, they didn't have to explain how and why they exercised the powers given to them.