Well, you'd end up with something like this:

https://www.mtholyoke.edu/~wang30y/csp/ParabolicDish.html

GaAs panels have ~40% efficiency. It's not easy/dirt cheap (you need high temperatures, and materials to go with that) to get that much efficiency out of steam turbine (or Stirling engine). For example your typical nuclear power plant would have about 33% thermal efficiency. And with the panels you have less moving mechanical parts that need servicing. And the panels are silent vs. steam turbine. Lighter also. Pure solar thermal has been tried/used many times before.