It all sounds so logical. "We have to prevent hate-speech from having a forum." or some other responsible sounding argument governments use as a beard to prevent people from airing their views freely in order to suppress dissent. Are people really so easy to influence that messages in the public realm have to be controlled by some government entities? One curtive glance at the antics of some self-proclaimed social justice warriors or the expletive-laden rants of heterophobes of all sorts might just cause a knee-jerk reaction to utter a sentence with the opening, "There outta be a law...", but lest we forget the sanctity of the principle of a free expression of opinion for fear of drifting off into a populist dumbocracy, give humankind some credit. Yes, there will be some idiotic discourse carried on, and some downright inflammatory rhetoric spewed, but this is also a learning experience for the participants and observers. People can change their views if presented with new information they weren't aware of. They can also be exposed and hung out to dry when propagating a totally illogical idealogy or standpoint. When these experiences are minimalized, the mechanisms for critical thinking and discernment in the brain atrophy. If left unchecked, or avidly encouraged, eventually, the "informed electorate" becomes disinformed and their conclusions illogical or they become incurious and unquestioningly accept whatever half-baked party line purported by those that manufacture opinion.
Even if a person is inclined to believe we all need some nanny-state institutions to protect us all from thought crimes, who would decide what should be censored? Should a war on words be declared? This would certainly lead to even more words, judging by the war on terror and the war on drugs. Who chooses those that censor information? On what basis?
The dangerous part for governments is when you see 95% of comments to an article, situation or event agree with your own point of view, but the government's policies are in stark contrast. That is when people realize they're being disenfranchised and the political system has been highjacked by interests conflicting with their own, which could lead to a call for transparency and action. The owners of the system are aware that it will only continue to be productive for them as long as people are unaware of this plight or at least inactive. The struggle between the interests of those holding the puppet strings and those affected by the puppets will always be at odds with one another. This is necessary, but the scales should hold a balance that allows both sides to exist. The elite are aware that if the change they would like to implement is too large, people will tend to distrust it, so they work with patient persistence toward a set goal, knowing the peoples' attention will be diverted, providing them an opportun moment to take another baby step in the direction they've planned. The non-elite precariat must be aware that these attacks on their autonomy are ubiquitous and that they must remain persistent in their resistance in order to avoid sliding backward on the slippery slope of serfdom.
So, if someone or some institution is trying to tell you, you'll be better off if some kinds of opinion are banned, don't believe it! That kind of power has always been abused historically and that road ends with a violent crash sooner or later.
The world is better off when the foolish are allowed to be fools in the public domain whether you enjoy hearing their foolishness or not.
If you must, try to show them the holes in their ideology without letting them get you too riled up. If you can, just chuckle to yourself that someone could express an opinion that stupid and carry on nonchalantly, for that person's right to spout ridiculousness is important for a working democracy and remember, you're not going to change hard-set beliefs in one sitting.