OK ..I know they don’t rust as much and are more expensive but I seem to remember there are other properties that stop them being a true panancea for their application. I originally thought that because stainless was a bugger to cut then it was very hard and durable so would wear a lot less but a bearing seller said otherwise ..can’t remember the details
enlighten me great font of knowledge!

Some stainless ball bearings (I presume you’re talking about ball bearings) are actually quite a bit softer than their rusting cousins. Perhaps they don’t take well to surface hardening?

Just checked one supplier for Rockwell harness figures:

Standard hardened chrome steel = 60-67 HRC

420 stainless steel = 52-55 HRC

316 stainless steel = 29-39 HRC

Yup, good for low load and low impact locations, and those with little contamination… Think food processing, underwater etc.