This seems wrong. Reasoning scales all the way up to the discovery of quaternions and general relativity, often requiring divergent thinking. Reasoning has a core aspect of maintaining uncertainty for better exploration and being able to tell when it's time to revisit the drawing board and start over from scratch. Being overconfident to the point of over-constraining possibility space will harm exploration, only working effectively for "reasoning" problems where the answer is already known or nearly fully known. A process which results in limited diversity will not cover the full range of problems to which reasoning can be applied. In other words, your statement is roughly equivalent to saying o3 cannot reason in domains involving innovative or untested approaches.