Things that keep D from evolving?

[cy via Digitalmars-d-learn]

On Saturday, 6 February 2016 at 10:29:32 UTC, Ola Fosheim Grøstad 
wrote:
> This prevents fast GC: Pointers.

Would it be possible to write a fast garbage collector that just 
didn't track any pointers? Just offer a head's up that if you use 
"this collector" and pointers on collectable data, you're gonna 
have a bad time? How limited would you be if you couldn't use 
pointers in your code? Do all D references count as pointers, or 
is it only the T* types? Does Nullable!T count as one of those 
pointers that can't be tracked quickly?