Ad companies take some percentage of revenue as a fee. If they're loosing out, then three other people are also loosing out:
* The advertiser, who no longer gets their ad in front of the right audience. Now they're stuck advertising their potentially excellent product to people who have no use/desire for it. Selling their product now costs more, and it might make an otherwise profitable product not work out.
* The content producer. The person who made that webpage/video/funny meme. They only did it for ad revenue. Now that revenue is reduced, they'll have to make do with a shittier camera or will have to get a side job.
* You. You now have to put up with more lower value ads. They tend to be less useful to you (you might think normal ads aren't useful, but these are even more annoying and even less useful). That on top of the shittier content and fewer worse products available to buy from the above two reasons.