The "wisdom of crowds" depends on the question asked, the algorithm used, and the countermeasures that keep people from gaming it.
A simple example: if you want to have good restaurant reviews, it's a good idea to exclude people who never ate at the restaurant in question. That alone isn't necessarily going to get good results, but it will help.
Just letting strangers do whatever they want in group activities online typically has bad results. This has been tried many times. If you want to get good results you need some kind of structure.
Who imposes this structure? The people building the system.
Trolls, bots, socket puppets, propaganda, gaming the algorithmic recommenders, flooding the zone with bullshit, etc.
CLICK AND WIN --- YOU HAVE (3) NOTIFICAIFIOTIONS
I hope it's sarcasm.
My goal is to break feedback loops. Authenticated speech empowers us (the receiver). Like spam filters for news (outrage).
I don't care if other people are gas huffing QAnon, just so long as I don't have to ever hear about it.