> I think you misunderstand what the phrase "for all intents and purposes" means. It doesn't mean "literally, 100% true" it means "for true enough for this argument".
Email addresses aren't in any way decentralised. Saying they are isn't true enough.
> What network does your blockchain run on?
The product in question _doesn't_ rely on ICANN, or Comcast running to your house; it can work without either of those.
xyr point seems to be that your claim that e-mail addresses are decentralized is faulty. No amount of "Well you are not decentralized in your block chain, either." is going to rebut that. Indeed, it actually reinforces the argument that your claim was faulty, by implicitly agreeing to it with a "but neither are you" response.
So perhaps you would like to now explain how e-mail addresses are a system without a centre. Bear in mind that you yourself have just made the point about ICANN being at their centre. (-:
Maybe I'm missing the point, and I would look to you to explain to me what that is. But I guess congrats, you don't rely on ICANN anymore...