[FBT]

Say what you like, there is an incentive in the opposite direction in the case of a blockchain used as a trust-store, which does not exist in the other cases you described. One could make a lot of money subverting a trusted blockchain, whereas Wikipedia vandals don't profit a cent.

This means that you will inevitably have massively funded efforts to subvert such a blockchain. One thing I know for sure is that simple financial self-interest is one of the most powerful things in the world. Every blockchain has that fact working against it. The reason they don't collapse is that on the other hand, they have that same force working for them as well. A volunteer blockchain like you propose wouldn't stand a whelk's chance in a supernova. Sorry.