Not strange so much as a matter of contrast in circumstantial demand and acclimation, which must be measurably different for the blind vs hobbyist. James Nestor, in his time with Bushway, was able to accomplish echolocation feats that astonished him. Though I don't think he ever argued that the ability is equal for the blind and seeing, he did seem to conclude that the ability isn't restricted to the blind. I expect it would require a rare and great dedication for the dilettante to compete with a serious full-timer, in any skill. Functional blindness is a very formidable skill, one that very few would (could?) optionally practice full time.