Nobody says "uses memory", you call that the stack, and that was the dominant calling convention over the last decades. It's not dead-slow, it's just not as fast as the new fastcall conventions via registers. "memory" is usually the heap, which is really dead-slow compared to the stack.

There are many VM's which do the same, they have the advantage that the GC does not need to spill all registers to the heap just to find the roots. All roots are at the stack already. Basile Starynkevitch's GC from Qish e.g. does it like this and is one of the fastest GC's around. The stack is always in the cache, and the registers can be used for more locals or intermediate results.