There was an article, I can't recall if it was a reliable source, that said the home field advantage is vanishing because "before" if many players were playing away they'd take advantage of their being away from home by going out, getting drunk and staying out late in the hope of taking one or more people back to their hotel. These days, if you're a star athlete you can live on Tinder and fairly reliably have someone turn up to your hotel room. You stay reasonably sober and get an early night.

I'd not be surprised to hear that this is complete nonsense, but it's a memorable story. A simpler version of this story is that people have steadily drunk less since WW2 when going out, and you're more likely to go out when away from home.