I think it mainly has to do with women's screening process. Women have to ignore or immediately filter out 90%+ of matches/messages online because they get so many. But if a man approaches a woman in person, they are at least going to be looked at and considered. It's a hack for getting to the front of a long queue.

In person also allows for demonstrating qualities that aren't apparent in a profile. People's vibes are often very different in person vs. online. A man approaching a woman irl signals courage and confidence in itself if done non-awkwardly, so that also gives a guy a leg up over a bunch of dating profiles that are unknown quantities.

Disclaimer: married for 9 years so this is all theoretical