BetterC and CTFE mismatch

[Sebastiaan Koppe via Digitalmars-d]

Right now I am building a betterC application and I would have 
expected to be able to use the D standard library in CTFE.

It seems this is not the case. Can anyone explain why? It seems 
to be an arbitrary limitation.

example: 
https://run.dlang.io/gist/8ee9456bfae061eba81c931999183e49?args=-betterC