I think it's more likely that the no iframes rule is there to prevent click-fraud. See for example https://en.wikipedia.org/wiki/Browser_hijacking https://en.w

I think it's more likely that the no iframes rule is there to prevent click-fraud. See for example https://en.wikipedia.org/wiki/Browser_hijacking https://en.wikipedia.org/wiki/Browser_hijacking for more on a kind of malware that injects ads into browsers.