"Market rate" is not sacred. There's a ratchet effect here: the potential upside for both the CEO and the people who decide on CEO hiring is extremely large, while the downside for both parties is artificially limited by corporate structures and liability law. Worst case for them is that the CEO parachutes to another company, and the other rentiers take a slight loss quickly made up by their other bets. "Market rate" means nothing when the market is so severely distorted, and the viability of the free market itself depends on removing such distortions.

As for aristocracy, where else do you think this ratchet effect leads? It leads directly to a level of inter-generational wealth disparity that is functionally indistinguishable from explicit hereditary peerage.