having the skill no longer makes things available. its just one of the requirements.
for making a palisade you have to have yeomenry sure. but until the ability is available you have to have made a glue before, made a rope before (requires husbandry) chopped blocks before, and removed something from a drying rack and removed something from a tanning tub before.
THEN it will appear as you have "learned" prerequisite skills to do it.
i think its all so people cant spawn toons and flood them with inherit LP to do crazy stuff on the fly.