This right here is it! Everyone is always focused on the main feature being decentralization, but decentralization isn't a feature, it's an implementation detail. Decentralization is certainly a requirement for these goals, but permissionlessness is the goal. I'll note that permisionless for users, in the ability to create accounts and send transactions is every bit as import as permisionless building.

This is why I think the term DeFi misses the mark a bit, because it's a nod to the implementation (decentralized) rather than the features (open and permissionless). But at the end of the day I think it's catchier than something like OpenFi, and the terminology is set at this point.