This is silly. Single women 28-35 are more likely to try different methods of dating because people in their late 20's and 30's are likely out of college (where there's a large pool of possible mates that are easy to find) and more likely to be settled into a life situation (where their circle of friends/acquaintances is stable and does not generate many potential mates) and more likely to be bored/done with the club scenes.
So, just like men, single women 28+ are more likely to want the internet to generate a pool of people that they might possibly date.
In case you haven't noticed, between ages 15 - 25 or so, even a somewhat above-average-looking woman wields sickening power over men. They're approached anywhere, any time, and they only have to.. exist.
Eventually this power wanes and she'll get approached less and less. This is the time when she might actually have to do something to find a man, and this is the phenomenon we're talking about.
Your word choices are offputting and, honestly, seem borderline misogynist.
Young women do not "wield sickening power over men." Some number of them may get propositioned by strangers a good deal (though, I would suggest, less than you seem to believe). That's not the same thing.
And, in any case, "not getting as many propositions from strangers" does not equate to "becoming invisible to men."
And, finally, your argument, such as it is, seems to be based on the belief that younger women derive most of their romantic partners from that mass of unsolicited propositions by strangers. This isn't particularly true, and it kind of staggers me that you seem to imagine otherwise.
If women 28+ are more interested in online dating, it seems very likely that this is principally because of a decrease in the number of qualified potential mates in their extended social circle, rather than the decrease in the number of unsolicited propositions by strangers.