I agree with KozmoNau7 here, so many notions of constructing some system that will somehow weed out the "bad" ideas seems misguided in my opinion. The reason is that these systems necessarily treat all ideas as equal valid inputs by requiring
anything be allowed. This is done when we have bountiful evidence to the contrary, evidence that fascism and racism lead to horrendous consequences if left to spread through disingenuous tactics and deception.
In fact, we humans already form a decent system for weeding out bad ideas/opinions, we just don't listen to our own past experiences on the matter. We found out that fascism is putrid and yet now we try to come up with a new system that will weed it out instead of just chucking it into the garbage bin and moving on.
It's not paternalistic or a dismal view of humanity or that "humanity cannot be trusted with such a dangerous idea", it's because the people advocating for it constantly lie about it and intentionally trick/indoctrinate others into following. Under the right circumstances of me growing up, I fully believe someone could have deceived me into believing it, so I don't think I'm better than anybody who got sucked in. We can trust in democracy as long as we take proper precaution against things that prey on the freedom of expression and association in order to remove those rights from others.
Put another way, what real benefit is there to "freedom of speech, except for advocating fascism" as opposed to "freedom of speech, no exceptions"? The US already doesn't have pure unrestricted free speech because there are exceptions made for outlier situations where free speech is not protected in efforts to secure the safety of others. That hasn't led to total collapse or censorship.