It will be worse for the employers than anyone else. McDonald's can train anyone to flip a burger, but if they are only getting 2 hours of work from someone they are net negative as the person training could do the job. With just a little experience though the new person can flip burgers on his own leaving the trainer to do some other station.
The same for every other job - you are either hiring someone who already has the experience to do the job right, or you are hiring someone for long enough that the time spent teaching them to do the job is paid off by all the work they do after they learn how to do it.