There's been a discussion on Twitter this evening about ad-blockers now that Apple has enabled users of iOS to install ad-blocking plugins into their Safari browser. Note that this is not at the OS level and there is no default ad-blocker. The user has to choose to go to the App Store, install an ad-blocker app and then go to Settings → Safari and enable the app.
As we all know, Twitter isn't ideal for conversations requiring even a little bit of nuance, so I'm writing my thoughts here on my blog where I have more room!
Personally, I draw parallels with the older printed medium of a magazine. A magazine has adverts printed on the same physical piece of paper as the article and also comes with lots of separate ads that are inserted into the magazine. I think that reader of the magazine is free to remove the paper inserts without looking at them, put them in the bin and then read the magazine.
In this particular case, I see it as no different from the Pop-ups section in Chrome:
Like ads served from a different domain, I see popups as "inserts", so I'm happy to have the browser not show them. Other people feel that disabling pop-ups interferes with the publisher's right to monetise and so allow all sites to show pop-ups.
It's all about where you draw the line.