While Golf games may be a "social experience", online play numbers are awfully low even during Tiger's hey day.
I can't speak for others, but the reason I personally don't do it more is because of the lack of difficultly levels/feature & input method locking/etc to provide a consistent and fair playing field (beyond just handicaps).
It's sort of a chicken and the egg thing.
Devs can say "most don't play online" as a rationale to not focus on the online features, but at the same time they aren't providing the features needed to draw many of us into playing online and change that statistic of "how many play online".
Chicken or Egg - Who's first? lol