My old 71 Dart vinyl top stopped at the top of the windshield. I think the later cars (73+) that don't have vent windows have the vinyl top that extends down all the way down to the base of the windshield.
Possibly the reproduction vinyl tops they sell today are one size fits all and come with the extra material? People might be doing it because the like the look of it, or just don't know what is correct for their car so they do it by accident???
Here is a 1972 brochure that shows the top without the vinyl going past the windshield.