"La plume de ma tante" is a well-known expression from French teaching, as it was done many moons ago: How to express possession. The French don't have our very handy 's to stick on the end of a word. So that's the only way to say "My aunt's pen"--"plume", in that case, going back to the time when one wrote with a quill.
Returning to shotguns and ribs, I'd suggest that "the world's best shooters" are a group determined by which ones break the most targets. And in most target shooting disciplines, the shooter is allowed to mount his gun before calling for the target. A raised rib simply gives him a more reliable reference point to tell him he has it in the right place than would no (visible) rib and just a front bead.
For the upland hunter, on the other hand, a rib adds weight. If you're walking and carrying a whole lot more than you're mounting and shooting, the weight saved by not having a rib, or having less of one, can make a difference. Probably worth noting here that you're not likely to see many swamped rib guns used by driven shooters. (These days, of course, many driven shooters are carrying those modern contraptions with barrels superposed rather than juxtaposed.) About the most "minimalist" rib you're likely to see on a gun at a driven shoot would be the Churchill variety, which extends the full length of the barrel but which narrows down very quickly from a wide start at the breech. They may not want extremely heavy guns (unless they're shooting extremely high birds), but they're not as concerned with weight as, say, someone out for a rough shooting day.
