“I’m sorry, (Neville) Longbottom, but I cannot let you into my N.E.W.T. class. I see that you have an ‘Exceeds Expectations’ in Charms, however — why not try for a N.E.W.T. in Charms?” (McGonagall) “My grandmother thinks Charms is a soft option,” mumbled Neville. “Take Charms,” said Professor McGonagall, “and I shall drop Augusta (Longbottom) a line reminding her that just because she failed her Charms O.W.L., the subject is not necessarily worthless.” Harry Potter and the Half-Blood Prince – J.K. Rowling
Let’s be honest; if their last name wasn’t Potter, Albus didn’t exactly have an open-door policy for his students.
Maybe he made a token gesture or statement about any student coming to him if need be, but when would that have been exactly?
He was usually involved in off-premises, non-Hogwarts related endeavors like creating the Philosopher’s Stone with Nicolas Flamel or searching for Voldemort or Horcruxes.
Considering how little effort Dumbledore put into administering Hogwarts, at least beyond putting up some powerful protective spells, he just didn’t really seem to be that into the job.
Gilderoy Lockhart could probably have done what Dumbledore passed off as headmaster duties, sans the defensive enchantments.
Consider what you would want from a headmaster or headmistress at a school where your pre-teen or adolescent teen attends and what McGonagall offered.
A professor who showed some concern for the direction and the future of her students? Check.
A professor who was present at all times during the school year, including holidays? Check.
How about a professor who voiced her opposition to a Ministry of Magic official in defense of a student? Check.
Here’s one; how about a school official who cared more about every student than just some of his favorites?
Would Professor McGonagall have made a better headmistress than Dumbledore was a headmaster?