I can't think of many instances of someone sharing a "controversial" opinion where they weren't just regurgitating tired old arguments that are trivially discredited. The easy response is: well if they're trivially rebutted, why not just rebut them?

That works once. Twice. Twenty times. It doesn't take long before these "just raising the controversy" comments overwhelm sincere and thought-provoking discussion. A rhetorical DDoS/DoS works the same way a technological one does.

There are a few small, well-moderated communities/outlets where people have gone a level or two past propaganda and stereotypes, but they come into the discussion with an open mind. I can at least feel like, if I found the right angle, I might persuade them toward my viewpoint.

And most importantly: people come into those spaces knowing what to expect. I expect to see some serious discussion over whether or not I deserve equal rights, for example, but I don't feel like it's futile the way I do with people coming in with a roster of thought-terminating cliches and propaganda as a cover for hate.