I guess it’s just the other way around: plug/unplugging them thousands of times wears them out. Leaving them in prevents also any oxidation effects of the contacts (depends on the used materials, of course) in the long run.
Wanted to ask a follow up question. In the case of outputs on gear that have nothing plugged in because they’re not being use, should there be something there to prevent dust from getting into the machine. If so, is there some type of official item that you would use?
You can use mini jack to jack adapters, or this kind of items.
My own way to do is to put some thick piece of fabric on top, it’s largely sufficient imo