Minimally practical users of magic—cottage spells, farm magic—and mediocre magi are aplenty. Nearly everyone that’s not squib or cathar uses some amount of magic everyday without even thinking about it.
The rigor of becoming a mage, wizard, or priest is lost on many who are sent by their families to study and bring their name glory, only to be dismissed for their lack of aptitude—or lack or fortitude. Interestingly, the better teachers retain a higher number of their pupils.
Although magic is something that can be grabbed by anyone with a mind to, it cannot even begin to be mastered unless the utmost beautiful web of understanding is woven in the mind.