Questions about the SLP profession

We talked about a stuttering specialization for SLPs. Now I want to ask
something that is bound to generate some heat ... can one become
a "stuttering specialist" WITHOUT becoming first an SLP? I am
interested in both issues of potential effectiveness as well as legality and
peer recognition.

First of all, I believe that there are already people in the profession
who are not SLPs and some are well known (am I right?). Whether or not
they are well regarded by SLPs is not the issue (or is it?). I simply wonder
whether it is really necessary to learn about other speech and hearing
impediments in order to become an effective stuttering therapist.

My reasons for asking are both "academic" and personal. On the academic side
is my belief that stuttering is fundamentally different from, say, aphasia,
and, as I expressed in other posts, studying neurology and psychology might
be actually more relevant to the stuttering problem. My personal reason
is simply that I have given thought to becoming a therapist but I am
exclusively interested in stuttering. Yes, one can pay "one's dues", but,
as anyone at my stage in life will attest, I feel I have already spent
most of my life "paying dues" and, at 50, I have very little patience
for dealing with stuff that doesn't go right to the core of what interests
me.

Granting that, to some extent, we always bring all of our background to bear in all our endeavors, how much of a typical SLP's academic and (non-stuttering)
therapy background REALLY comes to bear on stuttering therapy? How much
is "paying dues" (if you are only interested in stuttering)?