I don't do that because if a website or web service doesn't respect me as a customer, pushing annoying ads down my throat, I would rather stop reading/using it, which is a form of voting with your wallet. Instead I prefer to reward loyalty to websites that are tasteful and put users interests first. As an example, such a website would be Reddit.
Installing ad-blockers has the reverse effect of what most users want. Ads will become more and more intrusive and difficult to block. And by visiting such a website, you're still giving that website eyeballs, you're still passing links around to your friends, you're still rewarding them for their behavior. It's like hiding the cookie jar from a fat kid, then congratulating him for being fat.
Installing ad-blockers is also immoral, just as software piracy is. I've seen arguments of people that don't think so, but it's hard to justify the piracy of Photoshop when there are free or cheaper alternatives available, it's hard to justify the piracy of MS Office when LibreOffice is available and it's hard to justify using Google Search with ad-blockers when there are alternatives like DDG.
If you don't like the ads served, just don't freaking use the service/website in question. It's amazing how self-entitled some people are.
I have zero responsibility in the website business model. I don't want to see ads either on TV or on the web, I use the available tools. I've used ad blockers proxies since 1998 or so.
When some websites (reddit, osnews) ask nicely to deactivate adblock to support them, I do. When they whine about how that's their business model (like ars technica), I don't.
Oh BTW software piracy isn't immoral. It's maybe wrong, but morality has nothing to do with it. After all Photoshop and MS Office success rely at least for a part on software piracy. Furthermore, from your point of view Gutenberg was wrong because of all those poor scribes he put out of jobs by going against their century-proven business model. Does not make much sense, doesn't it?
This is not about responsibility towards a business model, it's more about rewarding good behavior and punishing bad behavior. As a consumer, you definitely don't want bad treatment.
After all Photoshop and MS Office success rely at
least for a part on software piracy
Companies like Adobe and Microsoft have pockets deep enough to ensure that piracy is kept under control. But the story is very different for small companies or independent developers that just want to make a living. Also piracy doesn't work in the same way for games, or other products that people aren't using on a daily basis.
That's why I consider piracy immoral - it kills small software developers, it perpetuates the monopoly of big companies and is simply unfair to the people that worked on that software, pushing them towards more control, flawed technologies (DRM) and server-side subscriptions (in which case users don't really own anything anymore, not even their own data).
However, it seems to me that software piracy is a given of the media; there is no solution to it. Remember the 1976 Bill Gates' open letter to pirates? It's like drug prohibition: there is one supposed "right" state of the affairs which is unattainable, but for some reason the pragmatic approach is taboo.
I suppose software piracy is actually closer to the "tragedy of the commons" mechanisms than actual theft.
For the record, I also pirate movies and music from time to time, because I live in Romania and getting certain music and movies is difficult - most content available in the US is either not available in my country, or is made available with a significant delay. I don't have access to services like Netflix, the content on iTunes is a fraction of what's available in the US, the local bands still sell packaged CDs and we don't have a local Amazon/iTunes, etc...
Fortunately for HBO Romania, they are airing shows as soon as they are available. I also go out to movie theaters, but I only go to movies that are worth it. I'm not going to go out for a subpar movie, but I would pay $2 for viewing it in my home, if only such a thing was possible as soon as they are released.
Basically these media companies are shooting themselves in the foot by restricting the availability of content. Too bad that we don't have a "piracy subscription" to be paid monthly, because I would gladly pay it.
"Most everyone knows that half.." - I think that statements needs to be qualified because as far as I have observed, only tech people approach targeted Google ads with this much skepticism that 50% of ads are scams and 50% are dubious.
(Your statements imply majority or near-consensus opinions; I see no evidence to support these assertions.)