He’s right. Women tend to prefer to be eclectic than to be doing one thing all the time, whereas men tend to prefer to be focused on one thing at a time.
The nice thing about being eclectic is that you have a varied interests, but the cost is that you don’t become as skilled, so you tend to earn less than somebody who has dedicated his entire interests into that one activity.
I think you’re right, but that’s also a generalization. Some women are focused and are willing to sacrifice everything for the job, but I daresay they are rarer than similarly driven men.