This TOS-only-cannon approach put TOS in complete isolation. The original Enterprise and her sister-ships would truly be "in the freezer". No Reliant, no Mirandas or other ships loosely related to the Enterprise at all. Just a very small number of "Star Ship Class" vessels and that's it.
I remember first hearing Chekov dictate the "Starship Reliant log" when I first saw TWOK and thinking, "Starship? That's not a starship!"