Despite the myth a handgun is every bit as effective as a long gun.
No. NO. And
Hell No.
Not even close.
A hand gun has one (and only one) advantage..
It is smaller.
Therefore it is less of a burden to carry, and more concealable, making it more likely to have on hand when needed.
Sorry, but that's it.
In no way, shape, or form is a handgun even close to being "every bit as effective as a long gun".
A long gun has major advantages when it comes to putting down a threat.
1. Number one on the list (and most important) is that it fires a
rifle round. You're imparting much more energy into the target with each hit. This is also the reason many people shy away from them for home defense. They worry about a rifle being too powerful to use in close quarters. This alone disproves your made up myth.
2. Your increased accuracy statement is true, but not just at longer ranges. At all ranges. The longer range is just a benefit of the more powerful cartridge, but it is the platform itself that gives you the increased accuracy. A long gun is a much more stable platform to shoot because it gives you 4 points of contact with the body, (both hands, shoulder, and face) and a longer sight radius.
3. There are pistol caliber carbines that give you the operational package of the rifle, but with the smaller round of the pistol, but they don't really offer any advantage other than being slightly smaller than a normal rifle, or less expensive to shoot. Unless you are going with a "good" pistol caliber like .357 or .44mag in a lever gun, you gain nothing (or very little) in the way of muzzle energy. Modern pistol rounds like 9mm or .45 ACP don't improve as much out of a longer barrel because of limited case capacity. (not enough to warrant not going with a rifle round)
4. If a pistol was anywhere close to being "every bit as effective as a long gun", every infantryman, in every army of the world would be so equipped... in lieu of his rifle.
If you chose to use a pistol for the defense of your home, so be it. This is your choice, and I wish you luck. However, do not do it thinking you have chosen a tool that's "every bit as effective as a long gun" based on some made up myth you believe... This is not the case.
Drill Sgt: What is your pistol good for?
Pvt: Fight your way back to the rifle you never should have laid down.