Well it does makes sense because this is the ground reality, not all startups make it.
Engineers never get preferred shares no matter how hard we try to think so.
Class shares are a thing to protect investor money not engineer interest.
But they are irrelevant in a successful startup and no one really wins in an unsuccessful startup. At most preferred shares get invested funds back unless the startup took some really bad deal with multiple liquidation preferences. What I would say is that in an unsuccessful startup engineers are likely to make out better in an acquihire than the investors do.
Class shares are a thing to protect investor money not engineer interest.