Well you see, most of the individuals I know who own rifles like that have nothing else to spend their money on, since they are depressed childless individuals or deadbeats full of regret who have no passion in life yet still go to work because it is routine and expected of them and they'd have nothing else to do anyways.
However despite the aimless unfulfilled lives they lead, they wish to convince themselves they are not consoomers but rather based individuals, and thus they piss their money away on expensive firearms instead of regular sheeple goods while pretending it is different.
AR-15s absolutely have their uses, but the kind of people who most frequently buy them do not.
ARs are a jack of all trades gun; they do most things reasonably well but they don't have the short range stopping power or lack of overpenetration a shotgun has, they don't have the range or flexibility of a .30 caliber rifle, and they lack the compactness and storability of a pistol or revolver.
What they do offer is a very user-customizable platform so that you can tailor it to your needs and comfort. It doesn't have heavy recoil like a shotgun or rifle typically does, ammo and magazines are generally very available as are people to teach you about the weapon.
Handguns are kind of a non-starter. They require a lot of skill and practice to use effectively in a stressful situation. This equates to time and money emptying 50-round boxes at the range. They're just as loud as a long gun, even magnum calibers aren't as powerful as a rifle or shotgun round. Handguns require a commitment to improvement to be effective as more than a deterrent. This is why a lot of cops just spray and pray with their Glocks.
My own home defense rig, well if you want to find that out, sneak into Red Hood's hideout after dark.
Ok, sure, if you're trying to defend a mansion.
In a home defense situation you aren't shooting someone 50 feet away, you're shooting someone 10 feet away.
Pistols or short barreled shotguns are going to be what works in home defense. This isn't a range, you need to be able to shoot people basically up until the point they're on top of you, and having two feet of barrel sticking out in front of you going around corners is lunacy.
Power barely matters, if you have armored men storming your house you have bigger problems, and again, use a short barrelled shotgun then if you're concerned about that.
I'm not even a gun nut, it's just basic logic that the idea of a rifle for home defense is silly.