Ad networks can easily work around this, either by requiring publishers to proxy their requests or by having lots of domain names and proxies, which can be dirt cheap. You can't block requests as fast as ad networks can add domains and ips.

Sometimes I wonder what keeps ad networks from becoming more aggressive. Wonder what keeps them from breaking the content and force users to disable ad blocking. Because I know it can be done.

It's probably because publishers don't want to piss users off. Or maybe it's because on mobile most clicks come from Facebook or Twitter or other apps using web views that don't do ad blocking.

Google hosts YouTube and the ads for YouTube on the same domain with obfuscated paths, so that won't work. About all you can do if you want to use the app is pay for premium or use something like Vanced which unlocks the premium features without paying.

The main reason content blocking works is because anyone can introspect webpages and the source is available for modification. When things become byte-compiled it gets exponentially harder, if not impossible.

Works less well on mobile, which is what most people use these days.