You are missing a core benefit, the P3 is also a tube buffer. According to Fosi, the P3 allows V3 owners to embark on a warm rich musical journey. The essence of tube amplification, experiencing the perfect harmony of technology and nature."
A side benefit is the tube rolling option; there are a lot of inexpensive compatible tubes to try. To further the analogy, its like rolling around on the forest floor near a clear mountain stream. You do not get that from a schiit EQ.
For me, is only other way to do deep eq in the sound and to add "fancy" harmonics.
For the first point i prefer DSP processing and for the second I use vinyl format and my cartridge takes care of that.