The ASR voice recorder app gets this right. It lets me use the full featured version for three days, after which I need to watch a few ads to get another three days. I choose when to watch the ads, and if I'm late there is nothing worse than a small nag at the bottom of the app. I actually now start every day with the ads, while I cook breakfast, and it is a positive experience. I could also just pay for the app and be done with them.
This means the ad was effective. But was it useful to you? Did it save you from having to look for it yourself?
If you were not thinking something like "I need a certain T-shirt" before this came up, it's likely the ad created a desire in your mind which you didn't have. You got manipulated successfully by the advertiser.
The meta point is that advertising has become so ingrained into society it really is difficult to differentiate if a need or desire originated intrinsic or externally. It's really great for companies selling stuff.
Also I think people pay much of the price of ads even if they don't view them, via increased prices. The trillion dollar advertising industry money ultimately is paid by consumers. It is a necessary cost to try to launch a new product because we are reliant on it for information and because all your competitors are advertising.