Straight women feel as much attraction towards beta males as lesbians. Functionality there is no difference between straight women and lesbians from the beta males perspective when it comes down to being desired.

Alpha males are all men whom women find desirable. Beta males are the unchosen. If you are a beta male (by not meeting a minimum threshold of criteria) you never experience being desired.

There are certain traits that alpha males have in common such as masculinity, looks, iq, potential to attain status that are thresholds to even being considered by women as a mate. Personality only plays a role once those thresholds are passed.

Some men simply don't meet the requirements. They are beta males and completely undesirable to women. Therefore I believe that sub-sexualities exist and that straight women are alpha-sexual as in they only feel sexual attraction towards alpha males.