Imagine stuff like vibe.d - for proper performance you don't want to make any allocations during request handling. Neither GC, nor malloc.
This is absurd.
O(1) malloc implementations exist, it is a solved problem. (http://www.gii.upv.es/tlsf/) TLSF executes a maximum of 168 processor instructions in a x86 architecture. Saying that you can't use that during request handling is like saying that you can't afford a cache miss.
