The sheep didn’t evolve like this. They don’t “need” us to give them haircuts. Think how that would even happen, before modern agriculture?? They were artificially selected to grow wool far too much, and they suffer, overheat and sometimes die because of it.
And even the sheering is horrific as it is often done as quickly as possible (time = money) with very little regard for their comfort.
The kindness they need is to be left alone and not bred by humans.