the blockchain itself does not necessarily need to store all the content. The static content / even the updates could be stored in the Interplanetary File System. What is needed to be stored in the blockchain in the end is just a hash of the content, that doesnt sound that expensive to me.
So yes, we could create a p2p wiki, and yes we could store the hash of it in the blockchain, and yes we could allow to make micro transactions (upvotes) for all content. The main problem we could run into is, that the upvotes becomes too much to handle. But this problem we have also now...