Yarn Tyranny (aka Yarnocracy of Evil) is common form of Craft Tyranny.
Yarn tyrants are big yarn companies that keep their yarn parameters a trade secret which is absolutely intolerable. Even most fundamental information such as the actual yarn color is clad in fantasy names that render comparison amongst the products of different yarn manufacturers impossible.
Yarn Pirates frequently publish tables for yarn conversion but many of them are legacy hunters, who just want their share of the golden fleece.
The Open Yarn Database is putting an end to the reign of tyrants and pirates by returning the power to the crafting crowd.