In what way does a play like Medea help the cause(s) of women? Does a woman like Medea hurt the cause(s) of women in any way?

Medea helps the cause of women by showing that, even in a male-dominated society, where women have no rights whatsoever, a woman can still show the strength of character to take control of her destiny. Abandoned by Jason, and having left behind her own family, Medea is effectively a non-person, a stateless refugee. As a woman without a family support network to fall back on, she's quite literally on her own.
This would be a huge challenge for anyone, let alone a woman living at a time when women were totally dependent on their male relatives. Yet Medea rises to the occasion, channeling her rage at Jason's betrayal into taking control of her life in a way that would be unthinkable for most of her female contemporaries.
However, the way that Medea chooses to do this is problematic, to say the least. This is because exercising control over her life revolves around causing death and suffering to others, most notably her own children. It says a lot about ancient Greek society that a woman can only act independently by engaging in such murderous acts. Medea's transgressions against society's norms may not exactly redound to her credit, but they don't say a lot for society either. In that sense, Medea's actions may undermine the cause of women, but they also lay the foundations for successive generations of women to take control of their lives, albeit without necessarily resorting to murderous violence and infanticide.

Euripides's Medea is often analyzed when discussing gender studies and Greek tragedies because of the actions of its central character. Medea is a woman who has been betrayed by her husband, Jason, and enacts revenge on him by killing his new wife and father-in-law, as well as her two children.
Feminist critics have applauded Medea's actions as a symbol of what a liberated woman can accomplish in the face of male adversity. Certainly, we see independence in Medea; despite Jason and Creon's best attempts, they aren't able to stop her from accomplishing her goals. From that perspective, Medea could be seen as a role model for women, as she doesn't merely stand around as her husband acts against her will.
But where people might draw the line is the severity of her actions. Medea murders her own children, who had no part in the devastation that Jason has brought to her. It's easier to sympathize with Medea's lust for revenge against Jason and Glauce, but murdering her children is a whole other ballpark. Some would say this hurts women more than helps them, as it shows Medea being just as destructive as her husband.
Medea deals with injustices placed on her in extreme ways. Should women take inspiration from her actions, or see them as an example of what not to do? You be the judge.