The rule could be anything, as funny or as serious as you want. The universe will progress in a similar way that it has up until this point, unless your changed rule prevented it from doing so.
Some examples might be:
- The invention of currency is not allowed.
- Iron is slightly less stable.
- The Ancient Greeks are able to cultivate Silphium, which does not go extinct now.
Granted, the vast majority of people are illiterate, as there are no longer competent teachers, we never make it out of the stone age, as there are no competent organizers.
I wouldn’t classify “teacher” as a “position of power” in the sense that people who are mostly interested in holding power over others want the position for that reason.
There’s a huge difference between “being interested in power” and “being interested in improving things for yourself and other people”. The one is selfish in nature, the other isn’t.
There is also a huge difference between wanting a position and being good at it.
And yet, instructors and teachers are in a position of power over there students. A bad teacher can ruin a subject for you, destroy your grades, and get you in trouble. I believe it fits within the definition.
That is the exception and not the norm