Regarding ropes, for most practical applications I can think fro the top of my head, tensile strength is not actually that much of a limiting factor (especially with dyneema), but more the abrasion resistance and how easy it is to handle a rope.

I mean, you could in theory rappel from something like 2mm dyneema line with very comfortable safety margin on tensile strength alone, but 1. keeping a say 60m long 2mm line untangled is a serious headache, and I would not be comfortable holding my weight on the 2mm rope while letting it scratch against a rock wall .