Cat fights are supposedly the way real women fight- we resort to cheap tactics and can't throw a good punch. Men are ashamed if called "you fight like a girl." It hurts to see that society continues to label women as physically incapable of harming someone or protecting themselves. Women are still labeled as weak and unable to fight- the media might recognize male boxers but few will report on female boxers.
Furthermore, there has been huge exploitation on this idea of "cat fighting." Many cat fighting videos have surfaced, as men apparently find it amusing to see women fight this way. There are sexual undertones hinting towards lesbianism in these commercialized cat fights. I find it disgusting how cat fighting has defined the fighting power of women- we are all not weaklings, and we don't necessarily fight in that way. The exploitation of cat fights has further tainted the strength of females- two females fighting are seen as a joke and now carry sexual undertones. I think this idea of women fighting as "cat fights" has significantly contributed to the idea that superheroines can only fight other women and not men.