Where a guy sits aginst a tree in fairly thick bush, or sits up one a tree stand over a pile of corn, or bucket of Timmy's (or whatever) donuts and pokes his deer usually on the short side of 50yards, the smoothbore does the job very well. The smoothie shooter can then load shot on the walk home and poke some grouse.
Of course, the same shot can be taken with a rifle, and that same rifle can take a poke across the 'park' or meadow at the deer 125 to 150 yard shot as you carefully 'stalk' along a trail through the bush (still hunt). The smoothbore is useless for that task.
To someone blessed with mostly long shots over wide open spaces, spaces where he stalks to get withing 150yards of his deer, elk or even moose, the rifle is the only weapon that makes sense.
Here, we can choose to hunt either way if we choose - from a 'stand' for close shooting with a smoothbore, stalking through tall stands of spruce or growling young pines, or by even sitting around wipe open spaces of huge logging slashes 1,000yards wide, then spotting and stocking around and across those slashes to get a 'close' 100 to 150 yard shot. So, for us, blessed with both situations, either gun can be effective as a ball shooting weapon to fill the freezer.
This same hunter can then shoot grouse on his walk home and if he wishes, just as many of us do, with our rifles. Here in BC, the rifle still has an advantage as not many guys here use a smoothbore with fine shot for grouse, modern or flint - the rifle does it, no matter what the caliber.
Many of us also have grouse loads for our modern big game rifles as well - either with cast bullets or jacketed. That's just the way of things is are. Here, the rifle is more versatile than a smoothbore. Back East in the tight bush, the smoothie would be the verstile gun, as the grouse are usually quite wild and at least in Southern Ontario, it used to be illegal to shoot one with a rifle - I never had the opportunity as they were wild flushers. I never saw one on the ground, yet shot hundreds of grouse when I was a kid. When you saw one, it was already head high and bugging out, straight away from you - in whichever direction they're headed, already 30 yards away and jinking through the trees. Dang hard shot with a modern gun, let alone a flinter. Better have a really tight shooting load in it.