It's not specifically about the DMCA; it's about legal issues in general. Intent matters in the vast majority of law. You'd be hard-pressed to argue in front of a judge that your intent wasn't to block this specific site, based on the sequence of events:

1. Site added to block list.

2. Site removed from block list due to DMCA takedown request.

3. Site block by new rule added that doesn't target it directly.

I can't imagine any judge or jury looking at that sequence events and then taking you seriously when you say "I didn't intend to block the original site".

The parent's point was more along the lines of: people in the tech world need to stop looking for technical solutions to all problems. Some problems are social problems, or legal problems. They should be solved directly, not with awkward (or possibly illegal or at least tort-worthy) workarounds. We talk about chilling effects and corporations engaging in anti-social behavior when they threaten open source and the open web in particular, but attacking social/legal problems with technological workarounds is itself also anti-social.

Not saying that technological solutions are not useful sometimes. In the short-term, you can often make a bad social or legal problem less bad by using a tech workaround, while simultaneously taking the long slog toward fixing the root of the problem. But putting tech band-aids over our problems and then walking away will only hurt us in the long run.

This is one of those areas where I'd say it comes down to your lawyer. I agree with the general premise being presented, that sometimes the tech community tries to use technology to circumvent problems that aren't technological. That being said, in this specific instance the most effective defense would probably be something to the extent of "Your honor, based on the advice of my legal staff and my own understanding of the law, I was not in direct violation of the DMCA. For this reason, it seemed only logical that the issue must have been that the manner in which I was operating was the problem and not the outcomes of my operation. For this reason, in an attempt to comply with the notice I received, I revised my software to remedy what I understood to be the problem."

I think it's about what exactly is the DMCA used against. My first thought was as well that they claimed the act of writing down the domain name somehow violated the copyright of their domain. That sounds kind of silly and if it were actually the case, I think a hash/regex solution would make sense.

However I think what actually happened was that the business is operating paywalls/"anti-adblocker-walls" for other sites - so they claim that blocking them constitutes "circumvention of protection devices" for their customers - which indeed would be far severe for adblockers if confirmed by a judge.

(That's my understanding, though I might have gotten it wrong)

OK, why not circumvent the "argue in front of a judge" aspect? Instead of a list hosted on GitHub, put it on some server that's very hard to take down, leased anonymously. You could get EasyList, and then add back whatever's been removed. And make sure that no logs are retained concerning user input.

Because that means you have lost and agree that you don't have a right to block ads.

You have it backwards. Being able to do it freely means that I have the right.