I don't buy that for a second. Where is the asymmetry on Google's end? Google has to stop adblockers everywhere, meanwhile, adblockers only need to have a lucky strategy once, and social distribution spreads it everywhere. It's exactly the opposite of what you assert.
And at the end of the day, the web page is rendered on hardware (a display) owned by the user. In the very worst case, the final bitmap being displayed could be modified to remove ads; this crude approach could not be stopped short of a totalitarian state (Google isn't quite that strong) or mangling web pages into unreadability (in which case they wouldn't get traffic so ads would be pointless).
But it would never get that far, for the simple reason of accessibility (i.e. for people with disabilities). Accessible websites are machine comprehensible, to a greater or lesser degree. What the machine can comprehend (in form, if not meaning), it can edit.
Imagine the arms race with a super fast 30 minute release cycle. Every 30 minutes a new updates comes, 30 minutes later a new counter measure.
During those 30 minutes of vulnerability Google is losing only the marginal cost of serving an ad-free search, a rounding error.
During the other 30 minutes ad-blockers will lose users. Users of ad-blockers are not fanatics, they have no moral issues with ads. They are normal people who are using ad-blockers because it improves their browsing experience. So what happens when these ad-blockers temporarily ruin the browsing experience? They'll temporarily turn off said ad-blocker. By the 87th time what percentage will have given up on ad-blockers for good? If that percentage is anything greater than 0% then Google is winning.
The race is not like the DRM arms race, it is more akin to the virus arms race. Users want to run untrusted code and said untrusted code wants to do something the users do not want it to do.
I doubt Google would be willing to do 30 minute release cycles. Like any large piece of code search needs to be tested before it is released, the tests alone probably take 30 minutes to run. Google probably could not update their code more frequently than once a day. Risking breaking the search webpage is too high of a cost. On the other end ad blockers don't have to worry about lossing millions of dollars a second if they introduce a bug so they can respond much quicker.
And at the end of the day, the web page is rendered on hardware (a display) owned by the user. In the very worst case, the final bitmap being displayed could be modified to remove ads; this crude approach could not be stopped short of a totalitarian state (Google isn't quite that strong) or mangling web pages into unreadability (in which case they wouldn't get traffic so ads would be pointless).
But it would never get that far, for the simple reason of accessibility (i.e. for people with disabilities). Accessible websites are machine comprehensible, to a greater or lesser degree. What the machine can comprehend (in form, if not meaning), it can edit.