In DnD 5e - Does anyone know what the rationale behind making the base DC of a spell saving throw 8 instead of 10? Most attacks, passive attributes, spell attacks use 10 as the base. The average of a d20 die roll is 10.5 (rounded down would be 10).
8 seems like a very specific choice and slightly arbitary.
This information is not included in the PHB, DMG or anything as far as I can tell. Have the designers talked about it anywhere?