Library Typedefs are fundamentally broken

[Walter Bright via Digitalmars-d]

On 9/17/2014 9:54 AM, bearophile wrote:
> Dicebot:
>
>> Is anyone aware why this counter appoach was used instead?
>
> It's not sound, it's a hack. Putting unreliable hacks in a standard library is
> very bad. It's even worse than the problems that Walter has listed for __COUNT__
> (I didn't ask for that count in my enhancement request. If you have to copy it's
> often better to copy from Lisp/ML/Ada instead of C++).

Even worse? How? (Yes, I know that if you instantiate it twice on the same line, 
you'll get the same value.)