iFrames and SafeFrames are free, DIY security tools with several drawbacks and limitations, and should only be seen as a baseline security measure for display advertisements.
Platforms and advertisers serving rich media often advise against these highly restrictive frames because they prevent the rich interactions necessary to display more lucrative ad types (i.e. native ads, video players, take-over ads), and often prefer friendly iFrames so their JavaScript can properly interact with the webpage.
And while you are able to serve standard display ads through iFrames and SafeFrame, attackers abusing browser vulnerabilities and cross-site scripting can still break out of the “secure” frames and attack your user with redirects and pop-ups.
More often than not, running a robust advertising campaign will have you using a variety of techniques, frames, and ad types, each leaving your site vulnerable to attacks in unique ways.
The only way to ensure your site is truly protected on every front is to sign up with a team of anti-malvertising experts that offer real-time protection from a variety of attacks.