Hmm... nice try, but I have to disagree.
Ads on tv get run no matter what. Even if you mute it, you still see it. And even if you don't pay attention, it's there in the background noise (which you hear a lot of even if you don't notice it). Advertisers thrive on this "subliminal messaging". It's how it works. You might not want to jump up and go running to get that product; however, after about 30 times of noticing it, or hearing a jingle you tend to remember it. And that's what they want.
Now, translate that to here. There are advertisements. PHPBuilder leases out web-space to the advertisers for a fee. PHPBuilder gives them XX spots and says that somewhere between 50 and 60% of its community will see them. That's pretty reasonable. Now, if everyone has AdBlock or filters installed, PHPBuilder no-longer receives that ad-revenue because the advertisers know no-one will see their ads.
So we're using up their bandwidth, using their server-space, using their electric, taking from the community, and not giving anything back. How is that not stealing?
A loose definition of stealing is taking a service/product without payment or taking something that isn't yours. You don't pay for the bandwidth or server-space for this forum (as you shouldn't). But, one way you help is by just letting the ads be seen. Now, since PHPBuilder can be classified as a service, you're utilizing this service without giving back (not talking posting here) because you're not helping generate revenue for them. But for those that don't block ads, even though they may be asking all the questions, they are giving back to JupiterMedia as an external force by allowing the ads to be shown on their screen.
So you are stealing. And it's not that they're not internet saavy; rather, it's that people don't want to see ads like 3 or 4 years ago (before AdBlock and pop-up filters) where if you went to a "free" site, you got 7 windows asking to look at the neatest stuff.
You brought up the fact that if ads were placed on the inside of milk cartons, you're not a thief. In all actuality, you can't use that as a comparison. No ad company would ever place ads there (or agree to). Now, if you were to say put an ad up on a billboard, and someone shot the lights out so it was not visible in the dark, that's a better comparison.
Now, I'll leave you with this little economic quote and end my tirade:
There is no such thing as a free lunch.
Think about that....