> Interface stability aside, what fork does is simpler: a copied process can rely on its environment matching its parent's enough for a large subset of the cont

> Interface stability aside, what fork does is simpler: a copied process can rely on its environment matching its parent's enough for a large subset of the contents of the duplicated address space to retain their meaning. Serializing a process's address space's contents and then loading it into an "unrelated" process later makes it more complicated to know what memory contents can still be relied on (e.g. ASLR, file handles, etc.). Everything you mentioned except for ASLR is a problem for forked processes, and it boils down to kernel state (file descriptors and signals being two that I can think of right now).