The one odd thing about the article is the use of the term "registered music therapists", a term which is being dropped in favor of an acronym indicating "board certified" by the national organization. I've stuck with the "registered music therapist" term because that's the credential I worked so hard to get back in 1980. That credential was sufficient to get the contract to work in the public schools in Texas back in the 80's and early 90's. Today it wouldn't be.
Also, my current project of trying to come up with materials for regular folks to use to increase and expand their music making is something of an outlier in the field. Most music therapists are working with clients with some sort of clinical diagnosis. My sense is that there's an unserved population somewhere between the clients of music therapists and the students in music education.