> The case of 38sp -> 357mag is a working example.
That was intentional on the part of the people bringing tree-fiddy-seven to market. Backwards compatibility to something cheap and readily available is a great way to ensure more people buy guns chambered in your new and uncommon at the time caliber. They could have made it forward compatible too (i.e. chamber tree fiddy seven in your .38) but didn't because that would have been wildly unsafe.
That was intentional on the part of the people bringing tree-fiddy-seven to market. Backwards compatibility to something cheap and readily available is a great way to ensure more people buy guns chambered in your new and uncommon at the time caliber. They could have made it forward compatible too (i.e. chamber tree fiddy seven in your .38) but didn't because that would have been wildly unsafe.