Though his brave is a relatively small company, they have enough resources to have developed, and continue maintaining their own low-level ad blocker, which IME has been just as effective as uBO, but is supposedly more efficient (since it's written in the R-word language and compiled into native code integrating deeply inside the browser):
I can't imagine what hoops Google would have to jump through to block third parties from integrating their own ad blockers. You don't need MV2 for that AFAIK.