If you want to serve different ads dynamically you'd have to reencode every stream on the fly or find a way to dynamically insert segments into the existing encoded stream. Not sure the second is feasible with current codecs.
You can do that with m3u8 files. This is done for example by Pluto TV. Sure it is easily circumvented by simply stripping out these URLs, especially if they are marked as ads (And removing a m3u8 tag)
But in the end it would be again an arms race of adblockers and Google, so it would change basically nothing.
