I would say that ALL internet advertising is over 90% ineffective. It's really a vicious circle. Internet ads can be for stuff without a lot of general appeal (and honestly the impression I have of most of htem is unless I recognize the manufacturer it's a trick or con or scam, and even those i"m not too sure about since google ads are hacked on a daily basis), so people don't click. Advertisors don't understand how come people don't click, so they make their ads louder and brasher and more obnoxious which annoys people (like those ones that literally take over your browser until you watch it all), so they block them, which frustrates advertisors because they just can't comprehend how come folks don't just LOVE their products, so they make them more obnoxious, which promotes more to block them......lather, rinse, repeat.
I had a site that I tried to support by not blocking ads, but once I got a 'you have a virus, click here to get rid of it' malware attack via a hacked google ad, I started blocking them there too. I would try to support the site, but then the page was coded 'can't see the rest til the ad loads', and the ads were so big and on such a slow server it was taking 45-60 seconds for a forum page to load, so blocked those. It's amazing how fast you can surf with ads blocked. the internet just flies.
Can't deny that it's a 'necessary evil' of the internet, but I also can't deny that the irresponsible behavior of your average internet advertisor has discredited themselves.
However.....you gotta consider the other side of the coin. Browsers like Firefox didn't make adblock, third party individuals did. just like third party individuals have written the various dvd ripping softwares. Legitimate companies won't condone or make software that flummoxes another (generally). It would not surprise me at all to consider that Apple, just like Mozilla and other browser writers could have been contacted by reps from various internet advertising companies with a 'don't get in our way, kay?' Just like TV stations work in concert with ad agencies to get ads on your television. Two companies in a partnership, or at least working together and respecting each other.
Internet ad companies are no different than program or app writers. All business partners in a way. Which is why I don't think you'll ever see a safari supported ad blocking plugin - as in coming from Apple, not a third party - any more than you'll see an iTunes supported DVD ripping plugin.
As for my iPad, I just take solace in the fact that it can't run flash so I can avoid most of the most obnoxious and bandwidth sucking ads out there, and hopefully avoid the various malicious ads and malware attacks.