Haven't data centers switched to RDMA already? Why are we still wasting time with this networking nonsense when most of the time we're just copying data from on

Haven't data centers switched to RDMA already? Why are we still wasting time with this networking nonsense when most of the time we're just copying data from one memory or cache to another, over a private interconnect? ;-) It seems that Osterhout's complaints about RDMA are about current RDMA implementations. I expect many of them are fixable. Osterhout's complaints about TCP are all valid, though he doesn't mention my pet peeve with TCP, which is that connectivity breaks when your IP address changes. And requiring apps to deal with IP addresses in user-level APIs seems like a mistake. Simple request-response RPC protocols were a good idea in the 1980s, and they're still a good idea today. I should probably read the Homa paper(s) regarding congestion control though, as it isn't covered in this PDF.