Can salt effect stainless steel with pitting? Yes it can, it's science.
Has to do with the chloride which is in salt, braking down the chromium oxide layer that protects stainless.
I suspect every manufacturer of anything that is stainless will know this from their research department with employees well informed of those facts and I also suspect when it comes to guarantees it would be negligent not to inform people of this fact which also qualifies as an argument for pitting.
Basically, yeah, it can happen but like most people here I've never experienced that with my own stainless but it's also true in all the professional kitchens I've worked as well.
I still think as a consumer there's a need to push the limits when it comes to them, the manufacturers using that excuse when it does happen, it's just not good business which I suspect "made in" will find out if they continue to push this line of reasoning, it's a small world now and everyone can be informed in a click of the mouse, it's just not worth it, and them making an exception is probably a good thing in the long run.
Could/would an expensive car manufacturer and I'm saying expensive as it relates to the pricing of "made in" as it relates to SS pans in general. Would Mercedes tell a customer that the stainless steel pin that connects and holds the actual piston to the connecting rod in the engine was pitted and the cause of the engine failure and unfortunately pitting can happen and is considered normal wear and tear and the engine failure is therefore not covered, yeah, I don't thinks so, lol.