Try playing around with this interactive graph, hosted on the same site mentioned in the article: www.babynamewizard.com/voyager . Not exactly a refutation of your hypothesis, but it does seem to indicate that both boy and girl names are following the same trend of increasing diversity over time, leading to reduced absolute dominance of any given name. If those trends are the same, and if we assume that both parents are just as involved in the naming process regardless of boy or girl, then it may be that there's not much of a difference in the faddishness of names.

If I were to propose a counter-hypothesis, it may seem as though boy's names are less faddish because of cultural tendencies to name children after biblical figures, of which there are many more men than women. Names like e.g. Matthew, Timothy, Benjamin are more-or-less timeless because of this (though of course they'll still wax and wane like any other), whereas people seeking girl names are relatively out of luck: you've got Mary, other Mary, um... Delilah (if you're okay with the whole "treachery" thing)... strangely Eve has never seen the same enduring popularity as Adam.

In a similar vein, it seems that boys are more prone to be named after ancestors, for which I offer the anecdotal evidence of how few women are "Juniors" compared to men. (And all of this is assuming western culture, I have no clue as to naming practices elsewhere.)