The thing is, if you take the doctors analogy, all doctors have to be able to diagnose, but not all will have a good bedside manner, they aren't taught it and whilst it would be lovely if they were able to develop an ability to say the right thing to put the patient at ease it isn't essential and many good doctors don't have that ability.
Teachers need to be able to explain concepts and ideas, they have to be able to manage behaviour and talk to parents, they must know how to assess progress and find solutions when a child isn't doing as well as expected, they have to have a good subject knowledge and have a high level of literacy and at least a basic level of numeracy. They must be able to plan lessons and mark books and be able to implement the latest government strategy. It would be great if they could spell as well, but many good teachers can't.