If employees were to do ruthless "business as usual", people would join a company, not work much, jump ship to another within a few months. Wasting everyone's time, energy and money. How does that sound?
In your analogy companies hire people, train them, pay them and their recruiter, have them not contribute meaningfully and then fire them. And this is profitable why?
You speak as if this is a hypothetical thing that literally no employee is doing? What it sounds like to me is how a certain segment of the employee population is already behaving, so you hardly need to hypothesize about how it sounds when you can just consult reality.