One obvious answer is that they believe that human flourishing is best obtained by letting individuals command the AI, rather than the other way around. OpenAI (and Anthropic) is in the end still run by humans who have concern for the human race broadly, both in and of itself and to ensure their personal wellbeing is maximised.

I doubt the truthfulness your second sentence. If they have concern for the human race broadly, they have yet to show any of it. What they have shown is a complete lack of 'alignment' (to borrow a tired term) with human values, laws and basic decency.

For that to be the case we’d have to assume some level of altruism, when so for we’ve only seen self interested actions whitewashed as altruistic.