If enough people say no, the employer will start hiring people who say no, or go out of business due to a scarcity in employees.
You could use that "logic" to say there will never be a war because nobody wants to kill another human.
It would only be so if there would be a free labor market - but there isn't. People HAVE to sell their work.
Your analogy is flawed because people go to war for reasons other than wanting to kill other people. They could have a dispute over land, trade, or who's in charge (Like wanting to remove someone from power). While, an employer is in the job market solely to make a profit. According to supply and demand, if there are no candidates, the employer will say "Ok, I need to change my criteria." or they will go out of business because they don't have any employees.
Exactly, people have to sell their work. That means their work has value, and not selling their work has just as much of an effect as selling it (if enough people do it). When people have to sell their work, someone has to BUY that work. Is an employer not allowed to check and see if the "worker" is as qualified as he appears? Personally, I would not utilize this method when hiring, but I think companies should be allowed to.