Comment by senfiaj

Maybe (I think it's possible in protected mode), but it still has an allocation problem, imagine there are programs A, B, C in the memory. Later, A and C are unloaded, leaving 2 free holes, totaling in 2MB. Now you want to load a 2MB program, but there is no unfragmented 2MB free block. The only solution I see, is to shift some loaded programs, which might be slow and even risky. Paging makes this problem much easier. Also, paging makes permissions and memory sharing more granular.