>>> has google ads been responsible for virus/malware in the past?
Yes. Very much so.
Look for "VLC download" for instance, the first ads should be adware sites that distribute a fake version of the software and they paid to get that top search position.
Not doing it in the first place, of course! Because this has happened with VLC (a fact you seem to ignore), maybe they fixed it by now, or maybe it's temporary, or maybe you're just not in the "stupid people that would fall for this" filter bubble, but for quite a while Google Ads have been responsible for serving malware and damaging people's computers.
Also just because they try and fix it after the fact for VLC, doesn't mean it's not still happening for all sorts of other software. Google's approach for curation of ads is just not suitable to be able to provide a platform this large in a responsible manner (and I doubt it can ever be, but that doesn't give them a free ticket to behave irresponsibly).
Maybe you've forgotten what this thread was about in the first place, but if their policy is "we will remove ads that contain/link to malware as soon as they are (made) aware of them", then:
1) it's still a perfectly smart choice to use an adblocker because you can still get malware from ads (in addition to many of the other reasons such as opting out of clickbait timewasters, whose "innocence" evaporates as soon as you consider their scale), and a particularly important and smart choice to install it on people's computers that would actually fall for such a fake download link, which is not the HN crowd.
2) as a publisher, I would DEFINITELY want a much tighter guarantee on not serving/linking malware than "we'll remove it when we see it" because now it's not just my safety on the line (or my father trying to download VLC cause I told him over the phone, etc) but my entire audience!
I know I am careful personally, what to click and install, but I honestly wonder how long I myself could keep a fresh Windows install malware-free without running an adblocker. Some of those things are nasty clever and misleading (not thinking about Google Ads in particular, here). Ever consider the amount of good those people are doing? The ones writing the adblockers and keeping the blocklists up-to-date? They are not even getting paid to do it. It gives me such a bitter taste, every time I see a website whining about my adblocker usage. If you care so much, why are you using a third party ad network. If hosting and linking and curating your own advertisements is too much to ask, well then so is me whitelisting your site, sheesh.
Yes. Very much so.
Look for "VLC download" for instance, the first ads should be adware sites that distribute a fake version of the software and they paid to get that top search position.