hello99
#1 IF 100% of girls were married at 25 there would be NO discussion. The problem is that at 29 years old (having dated 10 years) 10%+ of girls still single.
THAT’S a HUGE problem.
#2 There is absolutely no data whatsoever that the close in age shidduchim that have taken place over the last two years have any more shalom bayis issues than that which is unfortunately considered regular in our community. If anything they are likely to be better marriages (if only because of the numerous brachos from various gedolim re: the issue).
In fact the present situation where the boys hold all the cards is in itself very harmful for marriage. Evening out the playing field and dating on equal footing will itself go a very long way towards reducing shalom bayis issues down the road.