So, when did last time someone from the non-entity-caste arise to the Executive class, which, traditionally is "considered impenetrable"? Not even Heth did that (starting out as non-entity) and what he did there was basically unheard of in all of Caldari history. He's an anomaly.
I didn't say it was common, of course it's very rare. Heth is still an interesting example, as he started out as a Home Guard soldier. After he was dismissed (oooh, we can add "dishonored" to his description), he went on to become an MTAC operator - a miner in a mechanized exoskeleton. Not a "non-entity", but certainly just a generic blue-collar background.