I don't think slackers are the problem. But the unappreciated high performers.
The moment somebody gets a whiff you didn't reward one of your employees for their work is the time your organization starts its decline (people talk). Frankly, I don't think you can avoid it as nobody can be really objective and tunnel vision is real. I just take it as a "nature's" way to move forward - blindspots of one company become strengths of another one, and due to past history, people would really compete against each other because of past perceived wrongdoings.
Those of us that are trying to build high-performing organizations will still avoid and remove those types of people. And we will continue to reward and not take advantage of our people to fill our end of the bargain.
Further, those of us that are also highly self-motivated will continue to leave bad situations, not become slackers in response to being taken advantage of.