In fact, our reluctance to pay for any type of content has led to the state we are in today. Paywalls largely don't work for many types of content and advertising is much more lucrative for the sites you patronize. Who's paying for that "Which Harry Potter Character Are You?" quiz on Buzzfeed that you gleefully wasted 5 minutes of you life on? Certainly not you; it was the advertiser who paid in exchange for an opportunity to influence you in some way (either direct action or indirect branding).
When you think about the 'morality' of ad blockers, it's not about the ad networks that we're talking about, it's the publishing sites that produce the content you consume. When you block an ad, the network doesn't pay the site. Simple as that.