> it is usually better to address concerns from others, rather than to dismiss them

It is often better....

Many ideas are designed to be refuted. The refutation spreads the ideas. It is part of the strategy. A "mind worm" (to coin a phrase) only needs to be repeated and it will do its job. Refuting it is repeating it.

So dismiss the speaker, attack the speaker's credentials and motivations ignoring the ideas. argumentum ad hominem, whilst rhetorically invalid, is the best tactic in those circumstances.