By definition, the JD (Doctor of Jurisprudence) is a doctoral degree, see, because of the D in it. See also MD(Doctor of Medicine), DO(Doctor of Osteopathic Medicine), DDS(Doctor of Dental Surgery), OD(Doctor of Optometry), DPM(Doctor of Podiatric Medicine, …
Professional doctorates exist: cite
The earliest doctorates were in academic and theological disciplines - the doctor is, by definition, a teacher. Note the irony in basing the name of a research degree (PhD) on a word (doctor) that means teacher.
The MD, a professional degree, preceded the PhD in the US. The JD came in after the PhD.
As for the argument that a doctorate is a doctorate only if it is a terminal degree: that renders many of the doctorates in Europe and in the UK nondoctoral - are you arguing that the only real doctorates in Europe are the higher doctorates? The only real doctorate in Germany is Dr.habil.??? Really?
The distinction between a professional doctorate and an academic doctorate is that the professional doctorate is typically based on coursework, does not involve research, and is a precursor for work in a profession (usually in tandem with soem sort of professional board certification). A professional doctorate (in the US, at least) is an entry level degree for service in things like medicine or law, contingent on the passing of additional board examinations and certifications.
It is true that in the European and UK models that the analog for professions like law or medicine are rendered at the bacc or masters level: e.g. MBBS, MBChB, M.cand. and the like.
It is also true that there are additional degrees in these fields that are research/academic focused: LL.M., S.J.D., M.D.(UK) and are designed to support scholarly work in these disciplines.
The use (or lack) of the title “Doctor” is a matter of social and professional concern, and doesn’t invalidate the credential. Current customs vary, but the only people routinely accorded the courtesy are physicians(unless you’re a UK surgeon), academics in certain academic settings, and in some settings theological.