Sites that ask users to turn off adblock and block their content from adblock users are at risk from deranking their site in the search results.
Many SEO experts are now saying that user metrics such as time on site, session duration, pages per session and bounce rate are all enormous SEO ranking factors. And there's a lot of reason to suggest that these metrics will continue to grow in importance over time. By blocking your content to users, adblock or not, these metrics are going to take a substantial negative hit.
If a user is asked to turn off adblock or not view the content, many of them will simply back out of the page and click on the next link. This is a huge signal to Google that the other link should potentially rank higher than yours.
On top of that, by disabling adblock users, that is an entire market of people who could potentially become regular users of your site, share your site and tell their friends about it. Reducing accessibility of a website to a large percentage of internet users is an enormous risk.
By asking visitors to disable adblock, you risk those users going to your direct competitor. Thus strengthening your competitors and weakening yourself.
It's quite clear that if you force users to disable adblock that you will naturally gain more revenue by being able to serve up ads to those people who do, but the negative ripple effect and consequences of essentially banning a large percentage of visitors is so drastic that in the end I think it's rarely worth it. And it's the reason why the vast majority of sites do not ban adblock users.