Wikipedia became the user standard because the competitors (encyclopedias) didn't have an online presence. This would be more akin to trying to create a new, decentralized wikipedia now, to compete with the centralized wikipedia.
Those are not the same thing. "Decentralised" implies that the functionality is provided by a bunch of nodes that communicate together. A MediaWiki instance is a single website that doesn't communicate to other MediaWiki instances for its functionality.
It depends. I would have done better to put decentralised in quotes myself.
It was being used to refer to the fact that a company wiki isn't under a central authorities control. This was the common contextual usage of decentralised in this thread (stemming from the fact that all twitter accounts are under a central authorities control).
"decentralised" is such a mess of a term by itself.
"Decentralized", in computing, is pretty unambiguous. My Postgres database isn't "decentralized" because I run my own instance of Postgres. My Zookeeper cluster is "decentralized" because I can shoot nodes dead and the remaining ones will handle their business as far as continuing operation.
