That really irks me when I see people do that.
There are side exits up near the altars, and they have tinted windows. So if it is sunny and they open those doors, then a wild, bright ray of sunshine blinds everyone because the sanctuary is dark.
But once the “announcements” which are pretty small time, are done, then the priest has us say a prayer that is almost a litany really. It’s for our parish saint. Then he gives us all a final blessing.
I just think it’s disrespectful to leave before that. To do what? Get out of the parking lot faster than everyone else? I’d rather get that final blessing by the priest than be able to leave a parking lot faster any day.