German heavy cruisers tied down larger forces

Why do people rate German heavy cruisers so highly when their individual fighting qualities were limited?

Their value came from forcing the Royal Navy to guard convoy routes and maintain larger ready forces, not from superior one-on-one cruiser performance.

German heavy cruisers were dangerous because of their location, sortie timing, and potential effect on merchant shipping, not because each ship was unbeatable in a one-on-one fight. Wartime accounts also had an incentive to magnify enemy quality, since dismissing the opponent made victories look hollow and losses embarrassing. The Royal Navy had to keep enough cruisers and heavier ships ready to catch a raider that could choose when to leave port. Guaranteeing two cruisers against one German ship might require six ships in the area once maintenance and availability were considered. A modest surface force could therefore impose a much larger readiness burden on a global navy.