I think the popularity of content blockers is driven by it being one of the few (and very published) new additions to iOS9 that people see as worthwhile. Everyone gets that new iOS version and sees all the ads for “XX new things you can do with iOS9” and content is in there so people try stuff.
Marco also has a pretty wide audience of tech minded people who are more likely to want something like this too, hell I bought it because it has his name against it (and I use Ghostery on the desktop).
I’m the same, sites I like I whitelist to support them in a small way.
While it’s not a new thing, It will be interesting to see what putting content blockers front and centre on the mobile platform will do to adoption rates on the desktop and then if it will drive changes in advertisers behaviour. (and then will they get smarter in what/how they advertise or just sneakier in getting around the blockers).