Hmm.. .No. it's actually because Yoshi-P wants all jobs to have access to the same number of skills. Giving SMN, for instance, 7-8 primals to choose from would give them more utility than the jobs that don't have access to primals. So blue Mage would have to be implimented in a way similar to SMN or SCH as well. Like, you level up, do job quests, and gain access to a specific monster-type and a set of 4ish skills to go with it. If BLU was allowed to use any, most, or even several, monsters' abilities and customize which skills they used on top of it all, they would have to be seriously nerfed skill/damage-wise. This would make them less useful than the jobs with less utility.