Why aren't retired ships and tanks simply scrapped into steel and remelted?

Why aren't retired ships and tanks simply scrapped into steel and remelted?
Large integrated mills rely on basic oxygen furnaces, which supply over 85% of bulk steel output and demand clean, consistent feedstock. A single 250-tonne heat runs in roughly 40 minutes, so adding complex scrap from decommissioned equipment slows the cycle and risks segregation. A tank alone uses a dozen different steel grades across its turret, hull, tracks and wheels; mixed together, these off-spec elements make it hard to hit carbon, silicon, manganese, phosphorus and sulfur targets. One failed heat means heavy losses. That is why obsolete warships and armor sit in storage rather than flowing straight back to the converter.