Debugging compile time memory usage

[Bauss]

On Tuesday, 26 June 2018 at 00:59:24 UTC, Nicholas Wilson wrote:
> On Sunday, 24 June 2018 at 14:16:26 UTC, Kamil Koczurek wrote:
>> [...]
>
> If you were able to compile it with LDC and not DMD, then that 
> is most likely due to the LDC executable being 64-bit (limited 
> to available system RAM+swaps) and the DMD executable being 
> 32-bit (limited to 4GB).
>
> If you want to use DMD, build a 64-bit version yourself and 
> complain on general that the releases are not 64-bit.

Is there a specific reason why DMD isn't shipped as 64bit by 
default? Literally most machines are 64bit these days, so why do 
we limit ourselves to 32bit?