This looks like a paradox but it's easily resolved when you realize that trust isn't binary.
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.
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.