Why should an English teacher hold a degree like IELTS while he may be more competent than some holders of such degrees?

I just would like to clarify that IELTS is not a degree.  I don't believe it is necessary for an ESL / IELTS instructor, particularly a native speaker, to be tested. On the other hand, it would enhance the tutor's experience, so he could give practical advice on the exam technique.

An English Teacher should hold a degree like IELTS because although IELTS is a part of the ESL structure, it is different in terms of structure and focus. ESL includes a wide range of skills which can be explored depending on the students as well as the teachers. On the other hand, IELTS is much more focused and restrictive in terms of the skills involved as well as the time frame.

An ESL instructor can easily teach IELTS, but at the same time it is necessary for the instructor to do a deep study of the said course in order to assist the students in the best way possible.