Earlier quoted context omitted.
Well if nothing else, allowing such posts to propagate and be reinforced has the side effect of legitimizing them. Tagging posts as misleading is certainly one strategy, but people also complain about that being censorship or a conspiracy against them as well. Also if the argument is we should be moderating less, not more, then you're just arguing to turn mainstream social media platforms into those less well-monitor…
I wouldn't have an issue with some sort of shadow-blocking/ hiding of posts containing clearly dangerous misinformation. I'm not at all against moderation per se, but I don't think there's a simple one-size-fits-all approach that guarantees the best result for everyone. But I do have an overriding concern that ideas, no matter how crackpot, are best debated in the open rather than left to simmer in dark places.
The reality is that truly unfettered free speech & unmoderated discussions/debates devolves into all sorts of distractions from the primary goals of the platform (e.g. spam, hate speech, illegal activity, off-topic discussion). There must always be some level of moderation and censorship, even if that is at a basic level watching for spam bots & illegal activity. Typically that's not enough to ensure decorum, so you end up with additional community guidelines to set the tone for the platform.
My point here is that freedom of speech on online platforms is a mythical unicorn, that never existed, nor will it ever exist. It seems more like a wedge issue certain people like to bring up because they're unhappy with how a platform has acted towards them, and want to claim superiority by championing "free speech", even if they don't actually believe in it. For all the belly aching Musk did about Twitter, he is doing exactly the same things he complained about. That'd be fine, if he wasn't such a hypocrite about it & understood the ramifications and expectations of free speech, and the complexities of competent content moderation.
I'd also disagree that crackpot ideas are best debated in the open on social media. I think in a well moderated forum where people are held accountable, and expected to cite their sources yes. In the firehose that is social media where attention spans are limited, consumption is often on mobile devices which may hamper ability to do in-depth research, it leaves much to be desired as a place to find deeper truth easily. Also with puppet accounts, the moment you debunk one thread, ten more have popped up regurgitating the same talking points.