They do? Or they are not "ad-blockers" really.
The reasons ad-blockers block ads:
1. Ads are using user's data bandwidth, slow down the page loading and distract user from content they are trying to read
2. Usually it's not a single ad, but we are talking 4-5 ads with placement optimized to maximize clickthrough, while negatively affecting the user experience of using the page.
The above reasons apply for all ads, including context based ads. It's ads that annoy people, regardless of their context. Tracking is what annoys them on top of the ads.
> I don't mind simple context based ads.
Would you mind context based ads on your phone as you turn it on?
How about context based ads inside your car?
How about context based ads inside your house?
The only scenario in which any kind of ads are acceptable is one in where the user opts-in to see them.
Most ad blockers don't affect simple 90s type banner ads.
I use an ad blocker. I still get contextual ads on duckduckgo.com based on my search keywords. Most ad blockers focus on links to known global, privacy invading ad networks. No link, no block.
I don't mind simple context based ads. What I object to; and what I think most people object to, are personalized ads driven by privacy invasion.
Ads without proper context are mostly just an annoyance anyway and the associated personal data collection is subject to abuse. The only reasonable approach for a consumer is to block this crap until advertisers stop throwing money at it.