Qualification is another matter though the role of a teacher can be done by many people. As you say, Academical knowledge is the least important of them, and I can also add all the pedagogy thing, which ultimately is just nowadays a fancy word because it shows no tangible weight.

And the skills to teach resides in everyone because we all have the power to teach ourselves. And then we can analyze how this process takes place. Our brain is a sponge no matter how inactive it might be. And what is required is observation to identify the needs of each students.

Naturally, there are people that don't succeed in teaching in school, but that doesn't mean they can't. Probably, they're using wrong approaches or their idea about education is different. And when it comes to the aspects of life, sometimes we don't notice, that in a way or another, we're definitely teaching.