taught at an early age that helps prevent the shooter from using the closing defenders momentum against them and blow by the defender yet put the close out defender in position to contest the shot. Problem is a lot of the fundamentals kids get taught can get forgotten or become lazy habits.
In the highly competitive environment of college basketball and it’s focus on the 3pt shot, when a shooter on the wing gets even a little space to get a 3pt shot off chances are they’re going to take the shot. So players are taught to get there “at the catch”, and when they’re late closing out, they’re taught not to run directly at the shooter but to angle alongside their shooting hand and try to crowd or affect their release point. That is more effective than just running at them, plus you don’t want to run the risk of making contact with a 3pt shooter and sending them to the FT line.