So, if they offered a PayPal button, and I decided I didn't want to pay via PayPal, would it be okay to not pay in that case?
By putting up the blocker blocker, the site has clearly indicated how you can compensate them for the content, and the only ethical way I can think of around it would be to not consume it.
For crying out loud, what is wrong with people these days, are moral compasses so wacked out by constant corporate brain washing that people don't see there is simply no issue here. None at all. Not even from Facebook's point of view. If Facebook didn't want me to use their service without me seeing their ads, they WOULDN'T LET ME use it. It is that simple. No one is forcing them to let me in. Unlike a lot of their users who are in a real sense forced by their social connections to use it.
In fact it's hilarious how “anti-blocking” people here think they're somehow philosophically and ethically upholding Facebook's part of the deal–by driving people away from Facebook. It's the exact opposite of what FB wants and needs!
By putting up the blocker blocker, the site has clearly indicated how you can compensate them for the content, and the only ethical way I can think of around it would be to not consume it.