|(I think I did a decent job of softening the edges|
in this otherwise realistic acrylic painting of mine)
And even then, even when you’re trying to mimic a photograph in a painting (and why do that?), would it hardly ever need hard edges.
Hard edges are just that—hard. They don’t necessarily make a painting look more realistic. In fact, in most cases, just the opposite. They actually detract from the real-ness of the painting, in my humble opinion, of course.
In real life--if there is such a thing, and I’m not saying there is--when you view a scene or even a still life or facsimile of one, for instance, and even if you have 20-20 vision, the lines and edges are not razor sharp.
No, they fade into other objects. They vanish away. They are smooth, yes, but not so crisp and abrupt that they catch the eye of the viewer so that is the first place the eye goes because of the contrast in values.
Therefore, when you have “finished” your painting, you must go back over it and look for hard edges and soften them. Scrub them or dab them or re-paint them if you have to, but don’t leave them for the viewers’ eyes to immediately be drawn to.