If every software engineer can lift the share price by a hundredth of a penny every year, should the company give shares as part of comp to their 5,000 engineers or not? Should they even employ engineers at all?
The fact that some engineers can shirk and ride on the efforts of their peers does create a tragedy of the commons possibility, but the most appropriate solution there involves strong local leadership, rather than the conclusion that RSU grants are ineffective.
The point is that they are ineffective for the stated purpose of incentivizing the engineers to work harder. To that end, bonuses are much more effective.
The fact that some engineers can shirk and ride on the efforts of their peers does create a tragedy of the commons possibility, but the most appropriate solution there involves strong local leadership, rather than the conclusion that RSU grants are ineffective.