Networks don't say that. We actively try to block malware and accounts and have rules on content as well. Some networks have no issue because they don't accept 3rd party content or all the ads are created in house. Other networks are self-serve and let advertisers upload their own assets and script tags. This is, understandably, much harder to guard against.

My point is that content is offered for free in exchange for ads and the ad networks are enabling this trade of value, they are not actively trying to spread malware but a few bad actors do get through. Like they do anywhere.

And as long as those few bad actors are allowed through, users will be justified in their use of Adblock. Most people don't use Adblock because they think ad networks are actively malicious -- but not being able to be confident that NONE of the content they carry is malicious is a damn good reason to block ads.

Ok. You should also stop using your browser for letting the malware through, your OS for letting it run, your computer hardware for making it possible and technology in general.

Blame is a slippery slope. The fault is with the malware creators and them alone. They are committing the criminal/unwanted behaviour.

Top tier ad companies work very hard on this problem and if you check how many ads are run compared to just 1 being bad, it's a tiny fraction of a percent. Does it happen? Yes. Everyone on this site should already know there's no such thing as perfect security or a service that cannot be compromised given enough time/money. That's reality.

Please reconsider exactly who is at fault here for issues like this and hopefully you'll realize it's not just so black and white and this isn't quite a good enough reason to block ads. You can always use antivirus or malware protection software that's actually designed for this stuff if that's your primary concern.