I think that the first mistake people take when they read an article like this is that they immediately jump the gun and move from correlation to supposed causation.

Men who do work full-time, and who do get a higher education, may excel in other ways too. E.g. men who put in the effort to work a steady job probably are more likely to put in the effort to stay in shape than men who don't care to work. Or, another example, men who pursue a higher education often have to sacrifice things for it, and this perseverence/dedication points to a type of character that potentially could attract a mate. It demonstrates that a man is capable of putting in the work, and making a commitment.

I think instinct, consciously or not, impacts a lot of the choices people make, not only in dating but for life in general. Observing people on the street, for instance, our instinct is telling us a lot more than what we consciously see. There are prejudices we all form, subtle behavioral queues we subconsciously pick up on, and social assumptions we make without even knowing it, that all helps form the way we think of each and every person we know.

Working a steady job, pursuing a higher education. These are the observable qualities of likely dedicated, hard-working, virtuous men. Virtue, work ethic, and dedication are not generically measurable. But these qualities tend to make men successful, and successful men generally hold steady jobs and pursue higher education. Women want a successful man. I don't know any woman who wants to marry a loser. Why would she?