Playing Devil's advocate, their choice does have some advantages; for example, when a superior worker is sick, the loss of productivity is higher, especially if in the regular workers model they could get the other nine to work just 10% faster for a few days. Likewise, if one quits, not only there's more work per day not being done, as it might be harder to hire a superior worker.

Their model is probably less efficient during regular operation, but the variance when problems arise also seems lower.