It kind of seems like an insane TLD structure to begin with, right? I always thought .co.uk was bad (you're just pinning yourself to whoever owns the .co. part, but at least browsers have some suffix list where you can't, I don't know, hijack some login cookie for all of .co.). Joe Smith and John Smith can independently register joe.smith.name and john.smith.name, do browsers have a wildcard suffix list for the 2nd l…
There would be no issue at all if Verisign, or maybe Global Name Registry, decided to stick to the 3rd level registrations exclusively. Problem is, the chucklefucks over there decided it was a good idea to also hand out 2nd level registrations. Those 2nd level registrations outnumber the 3rd level registrations by an order of magnitude, so the PSL decided to just let joe.smith.name and john.smith.name share cookies. Which, IMO, was not a good decision, but it is what it is.