A mixture of heavy gatekeeping and limited market appeal for decades left women with less incentive to even bother with the music industry.

Where men had the option of going down whatever musical path and picking whatever style they wanted, women tended to be heavily manipulated and forced into a mold as soon as entering the industry. Record execs were more likely to finance attractive females and force them to dress and act a certain way.

It's opened up a lot in the last 30 years, but really until the 90s, why even bother having the dream if you were expected to be as pretty as you were talented and have your image completely created by men?

Carol King and Bobbie Gentry were both important figures in open up the market, as were Heart (and even Heart went through a period where all the shots were being called by execs for them). Also Linda Ronstadt, Emmylou Harris and Lucinda Williams.

The history of the Runaways and Suzi Quatro are well worth looking into if you're interested in the subject.

I'd highly suggest looking into Shelby Lynne. Country music was (probably still is) especially male dominated. She had no control over her career and she finally took the reigns herself with the release of "I am Shelby Lynne." It was the first time she wrote her own songs and picked the style of music she wanted to create and it was amazing.