If a company performs badly for any reason and this sort of system is in place then the employees are the ones who are punished, not the owners or shareholders. It's similar ro a variable-rate mortgage: These are set so that the bank always gets a profit no matter what the overall market does. If the market takes a turn that is unfavorable for the bank, the mortgage holders must pay more. In merit-bonus-only companies, the employees get less when the company does badly so that the bottom line can be maintained a little while longer and the shareholders won't notice.
And, the company is in charge of the metrics for your bonuses and compensation. If they want to cut staffing expenses, they just set cut-off goals for everyone that are unattainable. Poof. Their costs go down.
If these plans proliferate, we can expect a resurgence of unions. Workers who are accustomed to a steady income that was agreed when they were hired will not put up with this.