The Koch brothers have concentrated their efforts in states rather than in Washington. Right now they control 25 states and 32 governors. Should the Supreme Court ever kick back abortion to the states, I doubt the Koch brothers would go an a pro-abortion crusade. They have simply positioned the states to take advantage of such a ruling if and when it comes. Personally, I believe it will probably sooner than later.
So I don't see the basis for the claim they've contributed nothing of lasting value to conservative movement. One has to look at the overall strategy. They have nearly enough power to amend the Constitution unilaterally. RobSCIA v Trump updated score:CIA 3, Trump 2 13:08, 27 March 2017 (EDT)