But AdSense doesn't do a good job of it. I've seen ads that mess my browser's scroll bar, mine Monero, and pretend to be warnings from the FBI. That's why I use an ad blocker.

Frankly, you should take responsibility for every resource that your web page pulls down. I don't really care whether you do it yourself or have someone else do it, but if your ad network is serving up malicious JavaScript on a regular basis, then they're not doing their job right and you should fire them.