I've always found it strange that the most 'critical' job positions are among the lowest paid / furthest down the totem pole.

I work for a medium-sized established tech company. We've been running without a CTO and Director of HR for > 6 months. Everything has run smoothly. We've even had open positions for mid-tier management that have gone unfilled for long enough that they were deemed 'unnecessary' and the req was closed.

However, we had two of our operations people (one step above entry level) leave, and our regional office almost tanked completely.