RE: Byte-compilation warning in eldoc.el

[Drew Adams]

> > Thanks, fixed.  But curiously it doesn't.  You can call it (and I
> > always do call it) with one argument, as one does in CL.
> 
> Technically, you can call it with one argument.
> But in 99% of the cases it's a really bad idea.

Why?  What are those 99% (or what is the 1%)?
What's the (undocumented) behavior of calling it
with no second arg?  Isn't it just to use the
value of `obarray' (the standard obarray)?

What's the reason that the 2nd arg isn't called
out as optional, with the doc string saying that
it defaults to the value of variable `obarray'?

What's good about having an optional parameter
that's not advertised as such?  What's the real
point here, that calls for this exception?