Reason #2 at the link is why we absolute must have a reallocate-and-move primitive - because it could be much faster than allocating and copying: It would have

Reason #2 at the link is why we absolute must have a reallocate-and-move primitive - because it could be much faster than allocating and copying: It would have a higher chance for copying by virtual memory page remapping. Of course, just plain copying might also use virtual memory page tricks; I wonder which platforms do that (if any).