Sure, I’m not saying there’s no way of doing it, but a chat interface is deeply personal and not a space that ads have invaded quite just yet. If they want to show ad banners that’s one thing, but targeted diegetic ads are where the real money is. They can’t do that without compromising the chat experience imo.
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".