These days, most firearm enthusiasts use some kind of optical sighting device on most of their guns. Not just rifles, but shotguns and handguns as well.
There's a great reason for this. Simplicity. Aiming through a scope or a red dot sight completely eliminates one third of the complexity of lining up iron sights. With metallic sights you are required to line up the rear sight with the front sight and your target. With a scope, you simply have to line up your crosshairs (reticle) with your target. It's much easier to learn to shoot with a scope than iron sights, and since most rifle scopes also magnify, your target appears closer, and therefore easier to see, enabling you to place a more precise shot on your target. People with less than perfect vision are able to adjust the reticle focus at the eyepiece (ocular) for their particular eyes for a clear, crisp sight picture. Older eyes often have a difficult, if not impossible time trying to switch their focus from a rear sight to a front sight to a target as required without a scope, and it's frustrating to say the least. Scopes eliminate this frustration.