Pretty sure the reason people have that view of Zero Saber is because Nasu literally said she was a separate character
One of his interviews had someone ask about how they seemed different and his response was just "yeah you should think of them as different people"
I can 100% see Spacebattles STILL missing the point and thinking that doesn't matter when Saber at that time wasn't a Heroic Spirit and she was genuinely sending herself to both HGWs in her dying moments closer to a Counter Guardian than a Servant.
So yeah, Nasu basically went "yeah she non-canon as shit" because it's funny because Zero Accel Saber is actually is F/SN Saber in every way... and everything gets solved and bodied much, much faster for it.
