Any publisher with any sense at all knows that annoying users will simply drive them away. Then there will be no audience at all, except perhaps bots which can solve captchas.
I mean, that's what a pay wall is isn't it? think of all things people do on HN to go around those. Solving a captcha is probably worse because it's not annoying enough to go around so you actually just have to do it, but now it's more likely a legitimate user.
Any publisher with any sense at all knows that annoying users will simply drive them away. Then there will be no audience at all, except perhaps bots which can solve captchas.