The question is only how. Is it going to be by dictate? Is a church or government or institution going to enforce which ideas spread, or is it going to be free, spreading at the level of the individual?
There is no moral alternative to the free exchange of ideas. The only alternative is a restricted exchange... censorship and punishment.
And what are the consequences of that?
When people talk about the marketplace of ideas they tend to think of good, beneficial, ideas winning out over foolishness, conspiracy and just plain inaccuracy.
This has been shown up as naive lately. And if we really are talking about the "marketplace of ideas" being raw, Darwinian, strongest wins, then are we prepared to deal with the fallout of the fact that loud, motivated, well funded bullshit merchants will continue to have a huge grip over the public dialogue?
Because something is posted on the internet doesn't mean large numbers of people actually believe it.
There will always be "wrong" people. That will never change. But there is a degree of wisdom in crowds.
Proper education and "good" cultural values are extremely important and we haven't done so well instilling those lately.
Furthermore there isn’t a better alternative. Right now censorship from platform owners is abusively used to skew political discussions, using the pretense of factuality. I regularly see fact checkers make mistakes or make misleading claims or they inconsistent apply scrutiny. I see trusted organizations like old newspapers and health organizations (like the WHO) regularly make mistakes or sell their own speculation as incontrovertible truth. Trust cannot be given to a few lone entities. The marketplace of ideas doesn’t have this problem since it is decentralized.
How does something that isn't a marketplace of ideas prove it's dumb? Or should this question be punished by your algorithm?
In the face of hyperstimuli, we can't talk about mere human propensities as a justification, else we would have already turned ourselves into junkies many times over.
How many years did it take for heroin go from a cough medicine to a schedule I drug? Amphetamines, cigarettes etc.
There is a reason you can't put simply everything on the marketplace, and that is OK. That doesn't mean the idea of a marketplace is broken.