RE: buffer variable values

[Drew Adams]

> Another issue is backward compatibility.  Perhaps at one time the 
> function was commonly used from programs, but when the preferred 
> alternative was added they put that warning into the 
> documentation.  But the function still has to work properly for
> all the old code that was calling it before this.

Actually, I took a look at the Emacs 20 (distributed) source code before writing
that (non-exhaustive) list.  I didn't mention that point (a valid one), since
even back in Emacs 20 there were only a dozen or so non-interactive uses of it
remaining in the (distributed) source code, and even back then
`insert-buffer-substring' existed.

I might add too that my own impression is that Emacs Dev over the last few
releases has become more "generous" with such admonitions, prohibitions, and
prescriptions.  That's fine, as long as such are taken as guidance and not as
gospel.