The wool coats of sheep need shearing multiple times a year, and not just to make that new sweater you’ve been eyeing. For sheep to remain healthy, they need to shed their wool.
Whether it’s naturally or with a little help from human shearers, sheep need to shed their coats every year. Most sheep breeds can’t shed naturally anymore because it was bred out of them.
Some sheep breeds don’t need shearing because they have hair instead of wool coats. Most animals have hair coats and shed them naturally every spring. “Hair sheep” do the same, so they don't need shearing.
You can spin their hair, but most farmers don’t do this. Even so, Romanov sheep shed naturally and don’t need shearing.