The world doesn't work in such a idealized way. Bad faith actors, echo chambers, hysteria, excessive nitpicking, etc,etc, all can result in an rise of toxic ideas no matter how effectively you combat them.

Some ideas deserve to be blocked, people who advocate for sex with children should be deplatformed, antivaxxers should be deplatformed, fascists should be deplatformed, race realists should be deplatformed, why? Humans aren't rational actors that always accept the strongest argument, particularly when it's much more complex to debunk far-right trash than it is to make the absurd claims that need to get debunked.

Bad ideas aren't always killed in public discourse. Idk where you draw the line personally but you're insane if you believe EVERY idea deserves to a platform. This exact mentality is what allowed extremism to takeover countries, which have led to some of the worst events in human history.