rhollerithdotcom:

Also, some (e.g., the Man Who Is Thursday) say that the increase in female promiscuity has had a similar effect because (the thinking goes) once a woman has had sex with 1 or 2 extremely exciting men, she is less likely to settle for a LTR with a much less exciting one (and as long as she does not demand any sort of commitment from them, a woman using a "modern" sexual strategy will probably have sex with 1 or 2 extremely exciting men).

If she doesn't demand any sort of commitment from them, she can have sex with many more extremely exciting men than that, if she's at all attractive. Even less attractive women can similarly easily have lots of sex and non-serious relationships with men who are far above what they can realistically expect to get for serious commitment, even if they won't be extremely exciting by absolute standards, so the same principle applies.

There was a discussion of this issue on LW recently. If anyone's interested, these are my thoughts on the subject, and here I comment on some relevant research.