The issue is that subsidies at these levels create incentives for the development of inappropriate technologies. At a subsidy level of over ten times the cost of wind, RnD is going to be spent on not only technologies that are currently uneconomic, but also on technologies that do not have even a theoretical possibility of ever becoming economic. It is, simply, an inappropriate way to spur development. If a technology is so immature that its current costs are that high, appropriate government support for the field is "build a prototype in a government lab in hope of finding ways to lower costs" not "deploy whatever is currently sort of functional in the field"