Here is a little snippet from Suicide is for Mortals:
The pre-industrial atrocities of witch-hunting and witch-burning came to a close in Europe and North America in the early 18th century when it became apparent that no actual magic-handlers were among those persecuted and killed for supposed magical abuses.
Not all sorcerers have the skill set to defend themselves from mundane violence, but they do band together and protect each other. Prior to the Open Magic movement of the aforementioned time period, sorcerers generally kept their gifts a secret from the local populace. It wasn’t fear that motivated their secrecy so much as a sense of superiority. According to most magical historians, this sense of superiority began to attenuate when magic-handlers sought to increase their numbers by making an organized effort to discover and train individuals with previously misunderstood or self-suppressed magical talent in otherwise mundane families. It was this growing population of first-generation magic-handlers that alerted the magical community to the unfairness of allowing marginalized, defenseless old women to be scapegoated and executed for misdeeds they didn’t have the power to commit. The Open Magic movement grew out of this awareness, and led to the present-day magical culture of visibility.
It is not a part of the recognized historical record, but widely understood at the cultural level that the proponents of Open Magic were also the earliest opportunists.