So practical refractors are optically long. They deliver high magnification from conventional-length eyepieces, because magnifying power is simply the focal length of the objective divided by the focal length of the eyepiece. Refractors are optimal for viewing the planets, Moon, and Sun. Their unobstructed light paths deliver the crispest and sharpest images. Planets appear quite small in the sky, as do details on the Moon and Sun, so you want to magnify them a lot.
High magnification spreads out the image of an object, and that dilutes the light.
But planets appear quite bright, so there's no problem. The classic long refractor need, not be, therefore, too wide. The aperture gathers light, and the Sun, Moon, and planets offer plenty. This keeps the width, bulk, and cost of the telescope down. Peering Far Beyond Since the 1960s, observers have been flocking to deep-sky objects.