They aren't more malicious than billboards (which of course have been banned in some major cities [1]) or other public advertising, but they are equally malicious. [edit] Having said that, the 'security risk' angle does make online ads more malicious, potentially...

1: https://www.newdream.org/resources/sao-paolo-ad-ban

I subscribe to Netflix for that reason.

Online ads are not uniquely malicious, although they are more pervasive (even reading a magazine, the page I am actively reading will not have an ad in between paragraphs, though the next page might). I do think modern marketing firms (and often therefore web) have developed more effective -- and therefore bad -- techniques to have the effect they are paid for.

PS. I upvoted you because I don't think it was a bad question. If I had to guess, it may be misconstrued as a [bad] rhetorical question arguing that "you already have to put up with X, so it's pointless/inconsistent/illogical to reduce your exposure to X".

True! Guess a couple of banner advts on the side of the page wouldn't bother anyone, the intrusive one's definitely are the reason most hate advts.

Billboards don't reach into my pocket and try to steal my identification, nor do they spontaneously come-alive and follow me around the city in which I saw the billboard. My TV also knows very little about me.

I work in ad-tech. Let me tell you that online advts has access to a lot of info about you. Much more than you would imagine. So yeah, nobody said TV-ads weren't malicious, but ad-tech is taking it to another level.

I can ignore a billboard or mute a TV ad and the advertiser has no way of knowing.

They are malicious, too. But I can't block them just yet. (I'm eagerly waiting for an augmented-reality adblocker.)

That would destroy Nascar as we know it.

It would look like empty track with the sound of cars going by.

In those cases though, they are just there. They aren't scanning my irises for how many times I've seen them Minority Report-style.

...yet.

FWIW, I "block" TV ads by either watching the show over the internet and paying not to have ads (iTunes, Netflix, etc.), or by recording them on a DVR and skipping the ads. I avoid newspapers and magazines both because of ads and because the need for ad revenue has compromised the quality of the product.

Who says tv and billboards aren't just as malicious? Ad blockers make it easy to purge ads from my online experience. Fortunately, I just don't watch television and when I do, I always mute and look away from advertisements. Billboard advertisements is harder to control since I drive myself everywhere.

I don't watch TV (only Netflix) and wish there was an option for billboard ad blocking. It'd be an interesting art / social commentary project if e.g. Someone started draping black opaque plastic over billboards with drones and put the ABP logo on them. Feel free to steal this idea :)