I totally agree with you here, and have noticed a variety of attempts at rationalization.
My favorite is, "Why do you hate the Internet?!?" Since many things they like are paid through via ads, they see an objection to that as an objection to, e.g., news. I think this argument is dumb in a lot of ways, but the biggest for me is that nobody would have figured another way to pay for anything.
The next is, "Why do you hate freedom (of speech)?!?" This is usually phrased in a pseudo-first-amendment way, but as far as I can tell the real claim is some sort of might-makes-right, the-ends-justify-the-means, the-rich-can-do-as-they-please nonsense. All sorts of speech is actually illegal. E.g., fraud, solicitation of murder, conspiracy to commit murder, unlicensed practice of medicine, etc, etc. Capitalism is swell and all, but turning a profit is not a license to be a dick.
Another big one is along the lines of the Upton Sinclair quote: "It is difficult to get a man to understand something when his salary depends upon his not understanding it!" People who work in ads or for ad-supported companies can't see themselves as doing anything wrong, ergo manipulating people for money can't be wrong.
And then there's the one I think of as "suffer, Muggles". The logic goes, "I am smart and don't notice my being being manipulated by ads, ergo all the people who are manipulated by ads are dumb and deserve what they get." It's the same shick that you see whenever people get scammed. This ignores that ads and scams are both heavily targeted; that something is obvious just means they were going for another victim.
It all makes me crazy, though. We spend something like a half-trillion dollars annually on mass manipulation. The old justification was that people needed to be informed. That made little sense; the novel informational content of a Coke commercial is approximately zero. But now with the Internet, word of mouth is frictionless, reviews are free, and search is magic. Given that ads also obfuscate and confuse, I suspect their net information content is now negative. Might as well spend that half-trillion dollars on something that matters.