RDMA instructions are (1) more expressive than disk operations, from what I understand (support compare-and-swap, fetch-and-add, etc.) and (2) have different latencies and bandwidths (on the order of 1us latency, 20 GB/s BW).
This paper is mostly about proposing new RDMA instructions, such as a relative load/store, that could make remote data structures more efficient.
NVMe defines compare and atomic compare-and-write operations, but I'm not sure if there are any notable users of them. They certainly aren't exposed by typical file IO abstractions. There's nothing like a fetch-and-add in any typical storage protocol that I know of.
This paper is mostly about proposing new RDMA instructions, such as a relative load/store, that could make remote data structures more efficient.