If one has a shotgun that works for the job then often, IMHO, there is little need for an AR unless one wants one.
Mission drives the gear train..........
I know several guys who are avid bird hunters and VERY proficient with a shotgun. They probably should stick with what they know.
Other guys I know have been military and have experience with the AR15/M16 FOWs and zero with the gauge. They shouldn't get a shotgun unless they are wanting to get some time in on the system.
I know lots of rural folks for whom the shotgun is a ballistic multi tool, good for bad guys, bird hunting, recreation, and coyotes trying to get the chickens/cats/pups. For this sort of thing a shotgun with a couple of extra barrels is a superb choice.
I know at least half a dozen folks that have a quality pump gun with the first couple of rounds on tap being high brass #4s, followed by OO buck. Not a bad set-up for the mission they have at their home.
If one has none of those concerns then an AR can make compete sense.
Even though I am a former SWAT guy, have a personally owned patrol rifle on the books that goes to work every day, I am a carbine instructor, and have almost 40 years of experience with the AR system, my first go-to home long gun is a wood stocked Mossberg 500. I've got almost as much time on the Mossbergs, we carry those at work in all of our cars, I bird and small game hunt with a shotgun. and frankly, appearance can matter.
Anything I shoot a bad guy with will be locked up in evidence for a good while. If the bad guy I shot was a gang banger or has friends/relatives/whatever that are now angry at my for shooting him then I'd rather still have the AR at home at that point.
Most of my home defensive chores would likely fall to my handguns at any rate, just due to portability. Then there is seeing who is at the front door, which gets a little dicey to do when armed with a long gun.