In the Belgariad, we see numerous Grolims that have the Will and the Word, but very few other individuals. Why are there so few non-Angarak Sorcerers, none of any significance except for the followers of Aldur?
I don't know that there's a canonical answer, and Eddings is dead, so we can't ask directly, but the implication I got from the books is that using sorcery is incredibly dangerous, both to the user and to the world. A casual intent and word can cause catastrophe, and accidentally trying to unmake something will eliminate the sorcerer. Thus, Aldur and his disciples have only taught sorcery to a select few, and those only after establishing that they are worthy. In comparison, Torak is training as many of his people as he can to increase his power. He's consumed with revenge, so he doesn't care that this will likely lead to the death of many of his followers. So we have two sides, the ones who are only giving nuclear weapons to the select few they can trust and the side that's arming everyone because it's the fastest way to power.
There are a few outliers of course, such as Senji, who figure it out on their own, but the conversation in that chapter describes the danger to the untrained, how most of them wind up unmaking themselves.
Supposedly, the original Salmissra had some sorceror like powers, but due to the fact that Issa fell asleep before he could make her a full on disciple, so she dies and her successors have no powers. There is also the case of Senji, but personally, I have a feeling that a certain old man on a rickety cart helped Senji figure that stuff out.