Some people, after being exposed to misinformation, chose to believe them.
I don't believe in fighting "bad ideas" by suppressing them, I believe in shining a light on them. Let the truth fight for itself. (And of course now comes the classic counter-argument: that the evils of disinformation possess a virality that makes them spread far more easily than the truth, being that truth is nuanced and difficult to acquire whereas bad information is seductively simple. I won't address that argument here but personally I think it's a very dangerous way of thinking)
Do you have evidence that the truth more often than not win over lies?
It is possible that platforms, being designed the way they are to maximize corporations' interest naturally lead to unintended consequences.
There are billion of youtube video, nobody will be able to watch them all. So the youtube algorithm can recommend videos that are necessarily harmful based on what the person watched before.