The Question and Answer section for A Vindication of the Rights of Woman is a great resource to ask questions, find answers, and discuss the novel.
I know Mary's father would beat his wife (Maary's mother). He was an abusive alcoholic that took advantage of his wife. This surely would have influenced Mary's feminist writing.
Women not being at the social and economic mercy of men, including their husbands, would certainly have been modern for the time.
Wollstonecraft argues that women are not passive rather than they have been indoctrinated their whole lives to hide their feelings.