Ironic you'd bring up ethics in a discussion of ad blockers. Considering how radio & podcasts depend on sponsorship, isn't it unethical to remove ads that pay for the content? Effectively it is stealing.
https://current.org/2019/09/podcast-sponsorship-revenues-con...
I believe ad blocking is ethically justified on the grounds that it's just defending yourself from other's unethical behavior, and that you're entitled to do so - claiming otherwise would imply you're supposed to be forced to sit through entirety of a performance. That would be absurd invasion of your autonomy.
Also note that you are not paying radio hosts/podcast authors through advertisements. The ad network is. The exact payout structure is complicated and agreed upon without involving me the listener, but it boils down to parties speculating that a fraction of ad impressions will turn into eventual boost in sales, and money flowing from advertisers, through networks, to publishers, based on that expectation. At no point was I consulted in this, so I feel no obligation towards participating in whatever deals these parties set up between themselves - doubly so given that I'm being harmed by those deals.
Also, study the 101 of the domain. Like the famous Cialdini's book Influence: Science and Practice, or Cliff Ennico's How To Sell Anything To Anybody talks. Moral bankrupcy is in the very DNA of the practice, so no surprise that most ads just reflect this.