Yes, they mention that Fastmail, GMX, Inbox.lv, and Pobox also allow per-user DMARC overrides, including overriding reject policy. But Microsoft is the only one of these using MFEF forwarding which enables the attack to be successful.

I suppose similar attack to the one in 5.1 would work against Fastmail, but the victim would be able to see the original envelope from to detect that the mail is spoofed.