Where does this line of reasoning end though? Shouldn’t the browser makers be blocking the sites too? What about curl? What about the OS and local DNS resolvers (unbound etc)? Maybe Ethernet and wifi cards should contain blocking logic? At some point you have to draw a line!

I think there's at least one clear line between DNS providers and your examples. In your examples the enjoined parted is providing being a tool - a thing someone else uses - not a service where the enjoined party themselves does the thing.

It's one thing to say that you can't CNC machine guns for customers of your CNC-on-demand service, it's another to say you can't sell CNC machines because someone might use them to make guns.

Here the DNS service is being told they can't direct traffic to pirate sites, not that they can't give out tools (e.g. browsers or local DNS resolvers) that could be used by someone else to direct traffic to pirate sites (or could be used innocently). Your examples are all the latter - tools.

The way it worked is that the French government forced all major ISP to block some sites.

But using a third party DNS circumvents the block, so they went after them too.

Web browsers however (unless they include a VPN or 3rd party DNS) don't allow you to access sites blocked by your ISP. Same goes with ethernet and wifi cards.

I'm not saying I agree with it but that's the logic.

Potentially all of the above as long as they are not tested in court.

The line is drawn wherever a particular judge decides it's drawn, and each judge has a different ability to understand the broader implications of the line being drawn on any individual case.