Indeed, and there may be strong financial/legal incentives for doing so. Similarly, many developers may all be employed/funded by one organisation, and multiple clients may share large amounts of code (and be unable to avoid accepting large changes made to the upstream project).

So, while I appreciate the great effort to quantify the level of decentralization in the cryptocurrency space, I think the article mostly just exposes the subjective decisions being made by people who make claims about decentralization. Even that could be a big step forward for debating these technologies, though.