Earlier quoted context omitted.
The ethical issue is with regards to people reading all the content supported by advertising, but then blanking out all the ads. Marco's taking the position that, given the risk, and the general intrusiveness and privacy violations associated with advertising, that it's entirely ethical to do so.
Don't you think the bigger ethical issue here is how content providers keep using ad networks that commonly serve as a delivery mechanism for malware? Reading someone's content without looking at their ads seems like a relatively minor infraction in comparison.
I think a form of ads that are entirely reasonable (though hard to scale), are the ones that Gruber sticks himself into his DF feed. and, ironically, they are extraordinarily effective - I can probably name, by heart, about 20 of his sponsors. And I've visited, and purchased products from many of them.