I don't know what else they would really gain, or why else onBeforeRequest() was the most important thing to take away when extensions have so many other ways they can do harm.
Perhaps another way to look at it is not Google actively defeating adblockers, but giving a gift to their customers that pay for ads...making it easier for those customers to deal with the rising tide of adblockers, paywall end-arounds, etc.
This assumes that Google's ads will start to bypass the V3 adblockers. V3 in and of itself does nothing, Google's ads are still blocked by the updated adblockers.
> I don't know what else they would really gain
Well that's what I'm asking haha I'd like to hear from them on this. Even if some people at Google are nefariously implementing V3 for some future plan to bypass adblockers, surely some people at Google believe that there are benefits to the work.
What it really does is ensure that adblockers can't do heuristics, and instead have to rely solely on semi-static lists of urls. That's a nice outcome if you're a company that makes most of their money from ads.
There's not really a nice way to say that aloud though, so trying to make it sound it's a way of ensuring extensions honor privacy and security sounds better.