Quote Originally Posted by Nekodar View Post
The purpose of lower efficiency of those skills is to not have them break tuning.
The point is just that the lack of the skills means you don't learn your job as well as you should during levelling.
If the efficiency get reduced enough that it don't break the content (like not giving a job more effective defensive skills for lower dungeons than a class/job at the right level have), then you can also just ignore those skills.