Okay, I am just like an average learner but I'd like to share a piece of my mind on this. I think there is an element of truth when it is suggested that MSE usage should be abstained so one can think themself, but usually what comes in an exams or tests is not about how original one is but rather how well one can pattern recognize certain ways of solving questions/ proofs and repeat it .
In my personal opinion, if MSE makes the problems too easy for students, it may be time to trying giving problems to students which are more difficult and requires information of many different areas / MSE posts to answer.
Also, I don't really see the idea behind punishing a person by calling them a cheater because they are using every resource possible to them. In real world, the success would be measured by that instead of being able to blinding one self to search only in a textbook, right?
Anyways, big disclaimer: Just my opinion.