I might be wrong, and I do enjoy manual flying whenever I can, however my understanding is that inside terminal airspace (RNP 1, RNAV 1), the Flight director must remain on and full use of automation is also recommended.
I don't think that we can comply with RNAV1 or RNP1 without a flight director.
I believe RNP1 / RNAV 1 is a navigation requirement that we must comply with, unless obviously some type of unserviceability.