Guitar and mandolin player (well, and a bit of fiddle from time to time, played poorly) here. That same mentality exists elsewhere in the wooden instrument world, more so with mandolins than guitars.
Though you didn't ask me, what are my thoughts? The burden of proof is upon the ones making the claim. Prove it instead of causing endless debate on the internet. No one has, of course, just like no one has proven that a $1500 ethernet cable makes your sound system sound better. IMO, there are a lot of things that can ruin an instrument. Dry environment (causes cracks in the wood). General neglect, fiddling with bolts you shouldn't be fiddling with. But being played by a novice is not one of the things that can ruin a wooden instrument. It's all smoke and unprovable subjective opinions.
Let me put it another way: the best mandolin I own sounds better when an expert player plays than when I do. Not just the skill of the playing of the piece (the expert and I can play a scale at a slow tempo for this demonstration), the actual sound of the instrument. Did the mandolin suddenly transform its sound because it knew a good player was holding it? No, of course not. What we have demonstrated, however, that an instrument doesn't have just a sound. Lots of things contribute to the sound, including who is playing it.
Though you didn't ask me, what are my thoughts? The burden of proof is upon the ones making the claim. Prove it instead of causing endless debate on the internet. No one has, of course, just like no one has proven that a $1500 ethernet cable makes your sound system sound better. IMO, there are a lot of things that can ruin an instrument. Dry environment (causes cracks in the wood). General neglect, fiddling with bolts you shouldn't be fiddling with. But being played by a novice is not one of the things that can ruin a wooden instrument. It's all smoke and unprovable subjective opinions.
Let me put it another way: the best mandolin I own sounds better when an expert player plays than when I do. Not just the skill of the playing of the piece (the expert and I can play a scale at a slow tempo for this demonstration), the actual sound of the instrument. Did the mandolin suddenly transform its sound because it knew a good player was holding it? No, of course not. What we have demonstrated, however, that an instrument doesn't have just a sound. Lots of things contribute to the sound, including who is playing it.