Such theories could be counterproductive to successful action. Accepting this rational, theoretical approach doesn't automatically imply being 'logical' or becoming a 'rationalist'. When they have one working theory many people think that's all they need. They often work on the assumption of a guiding theory that states, on the occurrence of competing theories, that one must be right and the other wrong. But they miss out a lot if they take this approach and may not be completely successful because of it.
Successful people seem to select theories like specific tools to perform specific tasks.
Some might argue that theoretical work is just too much thinking and not enough activity, it might even get in the way of activity they claim. But this is a strange argument, most of us have plenty of time for both. In the political context it is not likely that radical change will happen in the immediate future, so we are certainly not short of time here. Both theory and activity are interrelated and test and reinforce each other, but they have their own spheres of application. Sometimes just sitting and thinking before action is the crucial difference between success and failure.