It does allow a couple of nifty tricks, like pervasive binary patching (if the program is chunked into relocatable object files, then you're no longer constrained by the original program memory layout when patching/replacing stuff). It's also useful for decompilation projects, where you can reimplement a program one piece at a time until you no longer have binary pieces left and still create a fully working program at each step (you don't even need perfectly matching decompilation since the linker will mend stuff back together anyway).