Oh, I had no idea they started adding domains like blogspot.com--that's clever! They must have just started doing that recently. And not quite as much of a hack as you say, really, since the justification is the same as the other suffixes.
The justification is the same, but it seems much less feasible to be "complete". There are a pretty manageable number of TLDs, and they generally have published policies about what they'll publicly register, so you can plausibly collect a complete list of which suffixes are public ones. But covering stuff like blogspot.com has to be done on a case-by-case basis and will be wildly incomplete. It mitigates the problem by including some of the higher-profile sites, but it doesn't seem like it can solve it generally.
