Those services either use really crappy (many false hits both ways) and heavy heuristics to try and determine that a pornographic image was downloaded and block it before display AND/OR a known "blacklist". So while you can outlist the compilation of said blacklist, someone still has to add sites that were confirmed to contain the material. Both ways are inefficient and spotty.
I admitted in my first post that you will never rid the internet of porn or make it completely unavailable to anyone. There is always a way around. But if the filter is good enough, unless the person is really determined, they will give up before they find its cracks.
Also, filtration is great for preventing an accidental stumbling-upon and so on.
A .xxx domain just makes sense, there's no reason not to do it. If you want to look at porn, you can find new sites by trying whatever, like, wallace_naked.xxx. You can filter for hyperlinks only to other .xxx sites. If you don't want to look at porn, you just blacklist the whole TLD and a great deal more work is done for you.
Again, you're right that there will still be porn on .com. I don't think anyone believes that's going to go away. But it's just a matter of simplicity; a .xxx tld helps everyone either way, so what's the problem?
I would be opposed to mandatory enforcement of this provision, but I think most legit porn producers will switch over for the citizenship points.