At primary school (UK) I was taught to write with a 'proper' fountain pen. Ink was in little plastic cartridges. We were forbidden from writing with ballpoint pens. (Calculators were also forbidden in maths.)

The reasoning was that fountain pens have more friction. I think it was related to how hard against the paper you pressed. You could hear the scratch of the pen on the paper. This allowed the pen to flow easily in some directions, and with more friction in the 'wrong' direction.