What independent tutors? The text under the Runelord/-priest heading may be vague about what magic, but it is clear about the point limit. The table at the start of the runemagic section has to be complete, or would you print it under the various abilities...?
Anyway, that is what is written under the hero ebilities, and therefore the advantage of having them, which is what was asked for originally. You can ignore that text of course...but what would be the point of joining a cult then? If anyone can teach you to any level, why would you spend 50% of time and income?