The issue here is one party making money, without consent of any form, based on another party's published materials.
So, google’s search engine business?
That said, there is an argument to be made here. One that's included in the disputed EU copyright directive in the 'link tax'.
It shouldn't be illegal to not request certain parts of a site, and it shouldn't be illegal to choose not to render parts of a page. What should be illegal is taking credit for copyrighted material, and that's not what going on.
The issue here, as opposed to just stripping ads, is that a totally unrelated party is making money with ads.
IANAL, but I highly doubt that the government will mandate what browsers people run on their computers. Outside of North Korea, of course.
Unrestricted mathematics are too dangerous to be allowed to normal people.
Piracy is already considered theft. Viewing webpages without ads is basically “stealing” web content. I would not be surprised in the slightest if some big advertiser runs with this idea and lobbies for strict legislation. And they likely would succeed, quite honestly. Congress doesn’t understand adblocking or the internet, but they have a vague idea of digital piracy.
Exploiting this grey area in the law will lead to a response from the courts and lawmakers. That response might well require that browsers display pages exactly as the publisher intends.
In other words, the end of ad blockers and other tools, thanks to Brave.
(Not at all unlikely given that Google seems to want that too.)