No, for 95% of the sites I read, I don't need to accept any terms of service. Hell, even the ones I do, often don't mention anything about ad blocking. I can't see anything directly prohibiting ad blocking here on the Facebook ToS, for example:
https://www.facebook.com/terms.php
> how is this any different than signing an agreement with a lawyer
ToS and a contract with a lawyer are very different things. It is not generally a crime to violate a ToS, but rather, merely a breech of agreement, and they can refuse service in return. If I violate a ToS, they can block me from using the site, and that's about the most they can do, unless I intentionally harmed the company (e.g. hacked other user data or compromised their servers).
(In the particular case of Facebook, it would also probably not be in their interest to block me, because I post a lot of original content to the platform that causes other users to spend more time on Facebook, and my presence on the platform is highly likely a net positive for them cash-wise.)
I operate by morality, but my risk tolerance is bound by legality. For example, for any human rights issue X, will I speak out for X in a place that has free speech but not yet legalized X? Absolutely. Will I speak out for X in a place that I might get a $100 fine? Probably. Will I speak out for X in a place that I might get jailed or beheaded? Probably not.
In this case though I don't consider it immoral to violate certain ToS terms, especially when they track and sell user data and don't offer a clear opt-in/out option to that, and perhaps even doubly on the sites that I actively contribute useful content to the platform in good faith, and the legal risk is extremely low.
To use a non-physical example, how is this any different than signing an agreement with a lawyer to give you legal advice, receiving said legal advice, and then refusing to pay?