Some sites insist they won't let me read anything on them until I have disbled my ad blocker. How can I, when I'm not using any ad blocker in the first place?
So what's happening here? Who is lying? Nobody. Then what's broken? The ads. The modern Internet that's built upon the idea of making profit from spying on the users.
I know ads are the primary source of income that helps many sites survive. I don't want to block them at all. But what these sites call ads are not ads, whether they know it or not.
Somewhere in this Hacker News thread you can find somebody happily remembering "when internet ads were just static 468x60 banners placed on individual sites by individual advertisers." I remember that well, too. Such sites and ads still exist, but they are rare. Instead of these harmless static ads, most sites nowadays contain slots that get dynamically filled by some advertising company like Google. Being dynamic is good because you can serve more relevant ads based on factors like geographical area, but most of the time these ad services go one step further--they spy on visitors. In other words, scripts and cookies served by these advertisers are not just meant to display ads; instead, they are meant to collect more data related to you, technically known as trackers.
When ads are trackers, blocking trackers looks like ad blocking. I use EFF Privacy Badger and Firefox Tracking Protection   to block trackers (I notice them detecting more than a dozen trackers in any given popular and "trusted" site; exceptions are rare). Now you know why sites complain people like me are blocking ads when we are blocking trackers. We do not block ads. We block immoral and ought-to-be-illegal trackers, and if your ads are trackers, sites, sorry, but that's your fault.
Functionally, the ad blocker warnings on many sites aren't much of an issue. They are using some common warning system, and it lets you continue browsing even if you don't follow the instructions and refuse to disable tracking protection. That's good. I remember some of these sites being not so generous in the past. Maybe they realized they were losing visitors. Maybe the increase in public awareness and regulations made them change. Maybe they actually started thinking ethically. I really wish it's the last one. However, the problem we're talking about is still there: they say you're blocking ads when you are only blocking trackers.
Updated on 2021-08-09 to make it clear that anti-blocker dialogs on most sites are least aggressive these days, but it's still wrong that they say we are blocking ads.