We are talking startups: Your typical early employee that didn't grow past mid level dev is out of position by year four. Even though their options are vested,

We are talking startups: Your typical early employee that didn't grow past mid level dev is out of position by year four. Even though their options are vested, chances are that can't afford to exercise them, and will be worth zero if they quit. Therefore, firing those kind of people as a matter of course is probably not what they want. You joined early for the great equity (a bad idea in the first place). Imagine how bad it would be if you risked getting fired if you don't grow into a good architect!