We have some parents if fellow students of their children beat them, and they get to know about it the next day they will follow their children to their school and start picking up a fight with the principal of the school or teachers
This was a very frequent thing at the primary school I went to. Teacher getting harrased by students' parents was a very regular thing. Not that I'm saying that that is why, but most of those kids today are not very well as adults.
One of the major reasons I agree with letting children face their own battles sometimes is for personal development and growth like you rightly mentioned. If they don't learn to stand up for themselves and be their own people now, they'll suffer as adults.
Yes, if we don't allow our children to face their challenges by themselves they will suffer and they won't know the reality of life.