Why does D rely on a GC?

[Kagamin via Digitalmars-d]

On Monday, 18 August 2014 at 10:01:59 UTC, maik klein wrote:
> Does a GC still have advantages over heap allocations that do 
> not need to be reference counted such as the unique_ptr in c++?

Isn't unique_ptr unique? What to do when the object is non-unique?