Az
Calling it silly doesn’t make it less true. DY provided a nice post by a phd outling the age gap theory. In it the author identified the problem as many girls suffering from infrequent dating. DY (and yourself I thougt) agreed with this but contended that it wasn’t as worth focussing on as the marriage issue or that it to us a result of the age gap. I never saud girls dont get any dates. All I said was there is a dating divide unexplainable by the age gap, that is causing the “shiduch crises”
DY
As to silly criteria here are but a few. Color of father’s shirt (recent yated shiduch forum), the old cliches plastic table cloth etc, yichus, where in Europe the ancestors were from, demanding full support, age (this may be what has been confusing you, age is a factor but not THE cause), grandmother pushing a wagon, premature infant (recent ami column) etc.
This is what has changed in the past 15-20 years and what is causing the “crises” Not demographics that hasn’t changed