Chrome on Android is a different story though. Firefox on Android allows you to use add-ons for the web version of Firefox with no fuss. Why can't Chrome do the same?
Google, however, desperately needs mobile advertising, because people are using desktop/laptop PCs less and less (and more and more people use adblockers on these), and mobile advertising is the only space not yet "disrupted" by ad blockers.
Because I can't install Adblock in Android Chrome, I won't use Chrome at all. And because I like my bookmarks/history synced between phone and desktop, that means that I won't use Chrome on desktop either.
On the upside, this works in Chrome and in apps, so my mobile experience is ad-free without having to root my device.
Bit extreme, I'll admit...
Installing an ad blocker isn't as easy as installing an add on someone links, you have to actively search for it (and require root on Android? Not 100% sure about that. For chrome this is, I have ff on my Android).
The Chrome and Firefox browsers are skins over embedded Safari [1] + utilities (such as bookmark/password sync) (technically it uses UIWebView, which is Safari). So, it is despite Google's sincerest efforts that Chrome has adblocking on ios.