Linked from
The 13 pages that link to Carbon steel, each with the reason it gives.
SteelmakingBroader topic: It is the broadest family of steel products made by steelmaking.
IronworkingBroader topic: Carbon levels distinguish soft iron from many useful, harder steels.
Knife bladeBroader topic: It can take a keen edge but is more vulnerable to rust and staining.
BlacksmithBroader topic: Its carbon content governs how well forged blades and tools can harden.