And yes, at one point, the doctors said I almost certainly had MS. For exactly the reasons you stated: my symptoms were consistent with it. It was only when the antibody in my cerebral spinal fluid came back positive that my diagnosis shifted to anti-NMDA receptor encephalitis for certain. Prior to that, I already had a follow-up scheduled with an MS specialist. I'm guessing that was done because of how rare anti-NMDA receptor encephalitis is.
So it's great that with anti-NMDA there is an actual singular test to determine this, but given it's so rare and little-known, getting to that point is very much not given :-(.