The wisdom of crowds is a theory that assumes averages (or medians, in some cases) from large groups will be generally more accurate than any one individual in that group. While it might be tempting to simply agree with the majority to take advantage of this, the wisdom of crowds only works if individuals are willing to push against consensus, otherwise it becomes a self-referential feedback loop. This paradox has often been observed in poll "herding," where polls close to an election will attempt to mimic results from other polls, making the overall aggregate less accurate.
I think that generally speaking, groups should make decisions democratically, perhaps with slight variations to experiment with marginal changes and generate a larger body of evidence. Meanwhile, individuals who disagree with the status quo should be encouraged to voice their complaints loudly. Some of the complaints will be nonsense, but arguments will spread based on how convincing they are.
This is largely the aim of free speech. However, I think that social taboos can limit the scope of discussion as well. In some cases, it seems obvious that certain opinions should be widely unpopular. There is a lot of documented evidence for the Holocaust, which is in my view a pretty good reason not to be a Holocaust denier. If someone genuinely didn't believe in the Holocaust, I would respond by defending that evidence. Similarly, slavery is widely seen as wrong, and we spend a lot of time discussing why it's wrong. So while it can certainly be said that going against the consensus on these topics is taboo, I do not think the taboo prevents the majority of people from having informed opinions.
Take, for example, laws banning content that is vulgar or gratuitous, but does not produce harm directly. Many types of content fall into this category. For example:
(a) a banner of a swastika, or a banner with a drawing of slaves saying that slavery is good
(b) "rape fetish" content with consenting actors that nonetheless, depicts a character as being assaulted against their will
(c) animated child pornography (that does not use real-life children)
When it comes to the above, I think that arguments can be made in favor of banning these due to perceived harmful effects on society. I also think that a free speech argument could be made, saying that content can be gratuitous and shunned, but that the government shouldn't go so far as to ban content until it creates a clear and present danger. I tend to lean towards only banning content that violates someone's privacy or consent or incites violence—outside that boundary, not everything that is gratuitous or immoral needs to be banned by law. But that's not the point; I do think someone could probably make an argument for the other side.
The point is that an intelligent discussion can usually be had on (a) and (b). People will make arguments that (a) should be legal in the interest of free speech, and they will often defend (b) without reservation. But suppose we take the same free speech arguments that were used to defend (a) and (b), and use them to defend (c). Much of the time, when I have seen this play out, the people defending government restriction will no longer be interested in explaining why they feel the way they do. At most, a response will amount to a personal attack or some version of "just because you think something doesn't mean you have to say it." Presumably, many people think it is self-evident that animated child pornography ought to be banned due to its gratuitous nature. These people may have a point about banning it, but I do not think that the conclusion is as self-evident as they seem to presume. Arguments in favor of (a) and (b) are taken seriously, and the arguments largely take the same form as arguments against banning (c), so the taboo against discussing (c) seems out of place to me.
What's more surprising to me is that, while it seems rather obvious to me why watching regular child pornography is inherently bad (it's a violation of privacy), many people seem incapable of making this very simple argument. When Vaush compared child pornography to buying products made with child labor since both are produced by harming children, I was surprised to never see the obvious distinction brought up. You could simply say "using an iPhone is not violating someone's privacy, but looking at a naked child who is incapable of consenting is a privacy violation." Instead of bringing up this very simple point, people called his argument weird and creepy. Which was warranted, but probably should have been backed up with at least addressing the point he thought he was making. Some arguments deserve to be mocked, but if people seem incapable of understanding what is wrong with the argument, I start to question if those people are qualified to be mocking.
Crowds are often smarter than individuals. But crowds are smarter when individuals understand why they believe what they believe instead of following the crowd. If someone thought the Earth was flat, you would bring up all the reasons you believe it's round. And if the crowd says something is obvious, they're probably right. However, two caveats: (1) If the crowd is right, you should understand why before mocking someone who challenges it. (2) The crowd isn't right about everything. There's something out there that the crowd is wrong on, buried under all the things it's right about, but the fear of going against the crowd is what prevents us from discovering what that is.