... Why not?
There are 254 usable addresses per octet, so my math is running at 254*254*254*254 gives you the ip v4 address space (0 & 255 being unusable, obviously) which gives you 4.2 billion addresses, minus the ~600k reserved addresses.
254*254*254*254*254*254 = two hundred sixty-eight trillion five hundred thirty-five billion addresses.
Think about that for a moment. 268.535 trillion addresses. That .535 trillion? That's five hundred and thirty five billion addresses. IPv4 has 4 billion. The existing IP space would sink into this scheme without leaving a ripple.
A new top level block would be 1,057,227,821,024 addresses under this scheme. That's one trillion, fifty seven billion each. You could literally reserve a top level block to contain IPv4 (which would waste one trillion, 53 billion addresses), allocate the 192 countries in the world a block each and still have 61 blocks that size left spare.
Even China which has a population of a billion and a half would still have seventy addresses per person in it's address block. How is this not enough? How many do you think are needed?