>If you cannot censor away opinions, if suppression of ideas doesn't work then why in exactly these kinds of articles do people bemoan it as dangerous?

Because the unintended consequences are harmful to bystanders. Probably more harmful than to the intended targets, since they're already socially ostracized for their openly bigoted views. Take, for example, the recent upswing in deplatforming. Most of the statistical data seems to suggest that the masses have become more afraid to speak openly, but it doesn't seem to have actually stopped extreme racists from saying racist things.