Why isn't nerve gear a real console today?

I know it exists in Sword Art Online (its a big thing within the anime), where players immerse within the game via their consciousness as the device is “neura-linked” (because of BCI) whilst they’re online on a server (they’re not playing the game on a screen) the “closest” thing in real life is VR (oculus) headsets but it’s still external (your eyes take over) rather than internal (directly linked within the person’s brain).