Why the DMD Backend?

[LeakingAntonovPlane via Digitalmars-d-learn]

On Friday, 28 November 2014 at 19:59:40 UTC, Xinok wrote:
> Given that we have GDC with the GCC backend and LDC with the 
> LLVM backend, what are the benefits of keeping the DMD compiler 
> backend? It seems to me that GCC and LLVM are far more 
> developed and better supported by their respective communities. 
> They have superior optimizers and are better equipped for 
> migrating D to new platforms. On the other hand, from what I 
> gather, there's lots of work to be done on DMD on improving 
> support for x64 Windows and ARM.
>
> It's a genuine question, which is why I posted this to D.learn. 
> I don't follow development on the backend and overall I'm 
> unfamiliar with compilers, so I'm not sure what the benefits 
> are of the D community continuing to maintain it's own backend.

DDMD, bootstraping.
LDC and GDC are not written in D.