yikimpurkan.
As others have explained it is becasue then they had more oppurtunities to meet. More meeting = more “dates” = more marriages (when that is the goal of dating) it is that simple.
Furthermore the amount of hoops that had to be jumped through just to get two people to go out where no-existant.
As for chasidim it is simpler becasue while they do a lot of checking, once that is complete the shiduch is basically done, the couple meeting is a formality and rarley is a shiduch not gone through after the couple meets.
Strict matching of singles works, lots of dating works. Somehow we have combined the bad aspects of both and created a disaster that did not exist 50 years ago.
It has (almost) nothing to do with an “age gap” TM