The premise is that the average person puts in 10x the effort for a 1% return on investment. You are an employee, sure, but are "investing" the company in terms of life-hours you could spend elsewhere. Naturally, you want to therefore minimize work and maximize salary. The ultimate situation being getting regular raises by doing 20-50% less than is expected to you.
If employers don't want this the solution is simple. It's not finding these people and firing them. It's paying people commensurate to their effort like a real meritocracy would.
If someone can hold 2 jobs working at 50% brain capacity then they are obviously very talented and quite crafty. You pay this person enough, they will dedicate 100% of their brain to your project. The employer side of the equation is JUST as exploitative as the employee side. It's just far, far, far more common for the employee to be exploited. For example, via pagerduty, poor hiring practices leading to overwork, or overtasking.
This is wonderful. Anyone who is truly a libertarian should be encouraging this. It's the perfect free market solution to exploitative labor. You dont get paid past 40 hours for your salary. Why should you reduce YOUR OWN worth to make a company's bottom line bigger? Unless you hold ITM options in the company the answer is you don't and shouldn't. You should be exploiting them at every turn.