Because people are idiots and will try and self-medicate, potentially making themselves really ill.
Besides the scads of dubious (or outright dangerous) health-related videos on other topics, YouTube has videos of people flying "wing suits" and engaging in many other risky activities.
It’s not just the laymen getting censored. It’s everyone.
Also, no offense, but how little faith do you put in our medical professionals and scientists that you think they can’t discern the difference between wheat and chaff?
The other things is pushing narratives that directly contradict our scientific understanding to an audience of nonscientists. And to be clear, "Ivermectin might work and there are good studies in favor of it" is not in that category, but "Ivermectin is the cure" is.
I think the Pierre Kory and Bret Weinstein podcast[1] is on the border between these two (with a bit of motte and bailey). But to get more insight into how it's landing, check the comments to that video. Lots of people finding ways to procure it, conspiracies, and a strong overlap with antivax.
How do you know the audience are nonscientists? Why would that be so bad,are nonscientists to be kept dark until 100% agreement among scientists is reached?
Science advances on many fronts, not just in peer reviewed papers.
So no, we don’t just believe the BS we are being told on the internet.