I suspect, based on my own experience, that aiming error is not necessarily directly proportional to resolving power, but that the aiming mark and sight design play a part too. For example, with a ring foresight of suitable diameter to suit a black circular aiming mark, it is quite feasible regularly to shoot groups smaller than 1 moa, even if the naked eye could not resolve better than 1 moa at that distance. Back when I was shooting ISU smallbore I was doing it regularly, from prone unsupported, week in and week out. Change the foresight, or the aiming mark, and it becomes more difficult, though the eye's resolving power is the same.
With scopes with a crosshair/duplex reticle, I personally find that an aiming mark in the form of an X, preferably with each of the four legs tapered to a point at the intersection, makes it a great deal easier to wring out the accuracy of the rifle than, say, a circle or square. I also find that, all else being equal, the lower magnification sight picture looks rock steady, which helps confidence.
OTOH a bit more magnification, all else being equal, helps when the aiming mark is less than ideal - a small dull-coloured object against a dull background, for example. However, all else isn't really equal, as there are trade-offs to be made as you up the magnification, in such things as FOV, depth of focus, mirage etc.
In saying the foregoing I'm not taking a position on it, just reflecting on my own experience.
