Sharing knowledge and building a model based on that is still going to be cognitively consolidative even if later counteracted. For example in a jury system the jury has only access to evidence that has passed admissability challenges. Telling them something and later telling them to disregard any conclusions or impressions based on that is rather laboursome. The decision to disregard can be waeker than the reflex to integrate sensed data.
There might also be such effects that a person assigned a mine known to be of lesser yield might work on it less enthusiastically. If you think what you are doing is the best method known to man you might throw your whole mind behind it way more wholeheartdly even if your assement of civilizational peak is in error and due to ignorance.
Then there is the case when the combination of individual efforts would be more efficient / smarter than banding together to be smart. Establising a strategy that everyone things is sound and everyone can get on board can get a very small common denominator. Limiting the variety of psychological profiles working on a subfield can make it more internally coherent. You tell someone about berries and they try to “help” and end up poisoning themselfs or the whole tribe. A way of limiting that knowledge can’t be abused is to limit acccess to it. Berry picking adaptations might make you dangerous fisher so it might make sense that you keep the details of your methods within your own operations.