What’s being overlooked (among other things) is the fact that there’s a significant difference between a Rav or Rosh Yeshiva signing his name to a message that he approves of, or giving a bracha to an endeavor, as opposed to the same Rav saying that something is muttar or assur or strongly advised.
A simple interesting study might be examining ages of parties in recent engagements/ marriages in the immediate families of the gedolim DY is talking about.
(An illustration of the above might be the simcha guidelines – does anybody remember those? – and how they worked out in different communities: litvish/yeshivish, and various brands of chassidish.)