What I've also shown is the past, until now. I've shown a culture still catching up to where we were in the 60s. And from that, I'm extrapolating that materials science makes improvements, and how.
And I'm saying that something like a fridge used to last longer, and it's been 65 years, and now they appear to fail more often. From that, I deduce that fridges should be lasting at least as long, if not longer, and that this is suspicious and indicative of a negative incentive for longevity.
Some materials may need to be replaced, quite assuredly. You seem stuck on the fact that "Wait, we don't have this now, therefore, there's no proof it ever could be". Show me, you say. Prove it. But this is of course unreasonable, for this is not my field, and I am clearly giving my opinion. However, what's happening is that there just isn't much research into longevity. Instead, the research is into short-term suitability, and warranty issues.
You cite that there are incentives in other areas. And indeed there are! But only to a point. There is low incentive to make cars last longer beyond a point, and the same holds true for products for the military. We've abated oxidization to a point, but further research, or more importantly implementation of that research, would only hinder sales on any front.
All that said, I don't think we're going to persuade each other of much beyond what we've said. You want proof, but all I'm willing to give you is deduced proof predicated upon my life experiences. Nothing will emerge beyond that.