You could choose to return fire from an active shooter at even a few hundred yards - think about a outdoor concert with the shooter up on the stage.
Even an only moderate freehand shooter may be able to make benchrest shots of great precision. If you're going to shoot at 100 yards, brace the gun against a post or barrier, cock the hammer and take your time (relatively).
A small revolver is capable of a very high degree of accuracy - much more so than a small auto. It isn't about barrel length or even sight quality. The ability to make a long shot is going to come down to:
- Understanding how much, if any, bullet drop is involved. (9mm pistols with 6 o'clock hold sights will shoot to POA at 100 yards.)
- Having a controllable trigger. It doesn't get much better than a cocked revolver.
- Having the gun sighted in. If you only shoot at 7 yards, you might not notice that your POI is 1" left, but that's 14" left at 100 yards.
- Have a reasonable degree of mechanical accuracy. If you're carrying one of those M&Ps that won't make 6" groups at 25 yards, it might be pointless to shoot a lot further than that.
You don't have to have high visibility sights, because you have more time to acquire a sight picture. This is when you use the crisp top edge of the sights, not the dots.