By and large, yes.
No one signs an agreement to go to a webpage and be marketed to. We didn't agree to it with television either. Ad-blocking is identical to changing the channel during TV. Advertisers have no right to expect that we are looking at their advertisement for any reason.
However, if there were some specific situation where a person agreed to watch an ad to see content, then I might think that would be an unfair breach of contract. Still, most contracts these days are not negotiated in good faith.