Think about how ad blocking works, and it's easy to see why the moral quandaries lie with the ad and content companies, not with the individual.
Ad blocking only works because ads are served from an entirely different site from the content. It’s how the browser can tell whether the content should be shown or not. Simple ad blocking will have a black list of advertising sites which it will reject. Privacy tools like privacy badger will ignore everything not from the originating site.
Many content sites claim this is a moral wrong. Blocking ads is depriving them of income. However, in order to hold this view companies must ignore their own moral duties, and we can see they have failed at every level.
The first question one should ask is: why not serve the ads from the same site as the content? After all, this would mean ad blocking would stop working entirely. There are many answers to this.
Firstly, ad companies don’t trust content companies. If a content company had to show an ad, they might simply not show it. If the content company shows the ad, it also has information about how many click throughs and purchases resulted from the ad. Ad companies simply do not trust content providers to accurately provide this information, as there is a direct economic incentive to lie.
Secondly, ad companies want to get more information on their users. If a content company provides ads to a user, the content company would have the data, not the ad company. Moreover, users can only be aggregated across sites if the ad company directly inserts and views cookies. Ads work the way they do to invade your privacy better.
Thirdly, content companies do not trust ad companies to run arbitrary code on their servers, so they prefer to ship that code to the browser. Instead of integrating with the ad company at the server end, content companies universally integrate at the browser end, thus worsening the user experience. Worse, they eventually authorise a third party to arbitrarily execute code on a user’s PC.
The justification for this sort of behavior is basically “it's cutthroat business,” but where’s the morality? If these companies cannot be moral, why does all the moral responsibility lie with the viewers? In the end ad blocking is sensible and only working against the most heinous intrusions into one’s computer. Unfortunately that intrusion is now "industry best practice."
Using an ad blocker is morally right. Don’t listen to the content companies.