Adblock Plus will then check the browsing history to see whether the user frequents this site (this could be specified for example as "visited the site on three days of the last week") and then display a notification
What is the point of having the META tag then? Why are they discriminating between users who have a meta tag and those who don't? Will web developers have to stay wondering whether increasing the size of their HTML is going to reap enough benefits? Can't they just do the same thing for ALL sites, irrelevant of the META tag or not? It's pretty obvious that if someone puts up ads on their website, they want people to view them and be interested in them.
To do nothing is to be nothing.