Guys that shoot quickly over pointing dogs probably don't need any choke and could probably use spreader loads too. Hell, they don't even need a 12 or 16 ga over a pointing dog.
Guys with flushing dogs have a little more distance to deal with quite often. But a half decent owner won't be surprized by a flush very often over his flushing dog. So he'll be ready to shoot.
Anyone that has hunted fields in the line abreast and blocker methods of the midwest will know that moderate amounts of choke are an advantage most of the time. A blocker with a full choked 12ga is at a distinct advantage over a guy with a cylinder bore gun.
