> LLMs can’t do ads without compromising the product.

It depends on what you mean by "compromise" here but they sure can inject ads.. like make the user wait 5 seconds, show an ad, then reply..

They can delay the response times and promote "premium" plans, etc

Lots of ways to monetize, I suppose the question is: will users tolerate it?

Based on what I've seen, the answer is yes, people will tolerate anything as long as it's "free".