There's no explaining the cluelessness of individuals or groups who seem unaware that they are their own worst enemy.
I would never but any product, no matter how useful, from an uninvited popup ad.
Period.
End of discussion.
Unfortunately, your outlook on these sorts of ads (which I agree with) only hurts the advertisers if every single other living human hates them as much as you do. The problem is they don't. These sorts of ads cost next to nothing to serve up, so even the tiniest response makes it worthwhile for the company.
This is why the amount of spam just keeps on growing even though 99.99% of the people getting it are enraged by it. The cost is almost literally ZERO to send; anyone with a broadband connection can become a spammer. (And if you want to be ultra sleazy, you can just use one of those five zillion AOL disks you get every month, sign up for the "45 day free trial" using a fake name and address, send your spam and then never access the account again. Then your cost is truly literally zero.)
Generally, a *cough* "legit" spammer will only charge you about $100 or so to shoot out your ad to several million different email addresses. At that price, you make a profit if only four or five people actually respond and buy your junk. (And out of several million people, you will always be able to find four or five who dumb enough to fall for your pitch.) If your spam goes to 3,000,000 people, five hits is a 0.000166% response rate. There's no other form of advertising on earth that can reach so many people for so little cost and guarantee you a profit on so few responses.
This is why spam is destined to get worse than it already is, much MUCH worse, to the point where it will start having a serious effect on the ability of legitimate internet traffic of all sorts - email, web pages, audio streams, everything - to get through ... because you'll never be able to eliminate from the gene pool that 0.000166% of the population that makes spam worth it for sleazy companies. Spam already makes up anywhere from 60-70% of all email; the estimates I've seen say it'll probably grow big enough to start causing serious slowdowns all over the net by next summer.