> It's pretty clear that Google's strategy is that making the web better for Google

FIFY.

I have no idea why the belief that "what's good for Google is good for the internet" persists - those days are long past. Google is best understood as a huge surveillance operation with bait services attached.

The obvious reason for them to push their own ad blocker seems most likely; it is to suck the oxygen out of the space by exploiting their privileged position as a browser maker to destroy 3rd parties that can block their ads. The ad blocker-makers are tiny, fragmented and unfortunately muddled with some crappy products that sell whitelist entries; this is a good time for Google to try to knife them, before a market leader emerges.