I'm reading about Intel's Total Memory Encryption and it's not entirely clear to me what function it serves. I understand drive encryption - someone steals your drive or, depending on how you configured it, the entire chassis, and it doesn't matter.
But while with some liquid nitrogen you could preserve the state of a DIMM and inspect it that seems farfetched. The operating system ostensibly doesn't see the encrypted memory - or it has to be decrypted on the fly. Plus the kernel is already keeping application space separate. Is it protecting an application from dumping another application's memory? If so, how does that work as the processor itself would be told to read the memory and it would ostensibly just decrypt it just as a SED drive is decrypted.
It is unclear to me from what type of attacks TME is protecting the memory.
In addition to the accepted answer I think @user71659's comment does a good job of explaining the commercial incentive for why it is worth protecting from a physical attack:
Physical attacks on the front-side bus to intercept memory traffic have occurred. Specifically, the original Xbox was broken this way, which is actually the origin of the feature. IBM implemented it for the Xbox 360, and AMD had already built SME for the Xbox One/PS4.