I think you're confusing boiling with searing. I guess anything could be a carcinogen at the right dosage but generally the advice is not to sear meat because that results in carinogenic particles. There is a similar process in deep frying.

But boiling is a different process, especially with tea where even if the water is boiling when poured it will rapidly cool down below the boiling point. As the article explains, boiling water extracts different substances to different degrees than warm/hot water. Specifically it will extract more of the bitter-tasting compounds and can break down others.