>Were a Proto-IE
> scholar to be taken back several thousand years BCE to the
> Pontic-Caspian Steppes, he or she might well be able to converse with
> the nomadic cultures living there.
I share your excitement over what historical linguistics has achieved, but I
can't share your certainty about our results! There are so many areas of
uncertainty that remain. Furthermore, each reconstruction is a snapshot of
the moment of splitting - and for each reconstruction that can be a very
different time. There may never have been a single spoken language
completely like our reconstructed PIE.
However, this shouldn't stop us from saying how great the achievement has
been.
Peter