Mobile users. There just aren't any pleasant ad free browser experiences for stock mobile phone users. Firefox for Android is quite poor and fixing through chrome requires root, something most users are not going to be doing
I couldn't give up background video/music, reader mode and the extensibility I get with firefox over Chrome now.
Edit: All content blockers either end up breaking sites or not blocking enough ads or both, it seems. Be prepared to long-press the refresh button on iOS to reload the page without Content Blockers if something breaks and you need quick access. See also, a list of iOS content blockers reviewed late last year at https://brooksreview.net/2015/12/content-blockers/
https://adguard.com/en/adguard-android/install.html#howToIns...
It seems to be reasonably low on the scum scale as far as Android apps and ad blockers in general go.
[1]: https://itunes.apple.com/us/app/adguard-adblock-privacy-prot...