"You generally won't get tight groups with a dot because of the dot size.
It's hard to hold an inch when your sighting device is 2" or more. They aren't for precision work."
This is generally true. To be more precise in accuracy,, figure out the intended purpose, and match the dot MOA size to that purpose. A 2, 3 or bigger MOA dot will translate to a 2', 3" or bigger dot appearance at 100 yds. At 100 yds,, a 3 MOA will look like a 3" dot. No way to get a 1" group with that.
But a 2 MOA dot at 25 yds can be pretty good at getting good groups. That translates into 1/2" at 25 yds. Dots are not as precise as the fine crosshairs of a scope. But they do have features that make them desirable for many other things. I personally tend to prefer the smaller MOA dots on all my guns to assist in getting better groups,, no matter the distance. But I also know their limitations.