Opera used to have opt-in content blocking and I used it for years without any trouble. I only blocked annoying ads on sites that I visit more than once. Of course it meant that I disabled whole ad networks sometimes, but that's entirely their fault. In the end, I was shown many ads while browsing.

That being said, Opera had a proper pop-up blocker and didn't implement every junk feature from javascript (prevent closing windows, change clipboard, ...). Disabling js (on per site basis) was two clicks away as well.

With Chrome, you can't really use it without ad blocker. One bad site and you end up with dozens of new windows, unclosable tabs, ... So the browser itself is yet another reason why people turn to ad blocking.

Opera 7/8 was way ahead of it's time. The tabbed interface was faster than Firefox, and better implemented, because Shift+Click opened new tabs, pretty much how I learned about tabs.

Ironically, the whole advertising system is set up to identify the viewer to the advertiser, not the other way round.

I built my own "opt in" by watching the status bar for slow loading sites and using the DOM inspector on visually annoying ads, then adding the host to my hosts file. It's very short: basically just google, doubleclick, outbrain, taboola.

http://pastebin.com/YAbJHe5j

Run any of the common apps like uBlock and disable the filter lists that come with it, then just add sites as you go. Same effect.

That would be like an anti-virus software that ran every virus it found and then asked you opt-out of the ones you don't want.