Hmm. Well I just thought about it a bit, and I do think you're right. Ultimately, the internet connects the world, and we're all the same people wandering around the planet as we are on the internet, so we should represent ourselves that way. I think many people don't realize that and as a result don't feel like they're being rude when they don't respond, but since these same people probably get annoyed by trolls (who flourish on being anonymous and behaving in a way only the internet permits) they are at fault.
This is a bit of a side track, but you know when you're walking on the street and someone passes you and you make brief eye contact and say "Hi" and they say "Hey" back? Well if you do that you also know that occasionally someone does not respond, or in the rare instance you fail to respond in time for them to hear you because they caught you off guard. And in these instances you can't pinpoint without a doubt that these people are pure bred jerks. They just had a little moment of technical rudeness that may or may not have been intentional. I think we just need to take that kind of thing into account when dealing with this kind of behavior online.
And also, in some countries, or even some areas of the US, sidewalk hellos are never exchanged. It's important to bear that in mind, but really I do agree with you on all this. Quite simply, it's impolite not to respond in these C.C. games.

See, that's great. At least the guy (or lady) tried. You have to applaud that effort.