Yata, Tokuoka, and a few others (mostly Yata), support the theory that it's not so much the occult idea of souls being trapped in a game, but the players being convinced the World is the real world, and mind over matter takes over from there. They momentarily "forget" That they're only playing a game, so once the Data Drain (which probably only keeps other people from logging in that character) takes effect, the mind is convinced they're dead and they go into a coma as a result. Hence why an AIDA-PC can PK someone and make them comatose without the use of Data Drain. A further, but less extreme, example is when Tsukasa, Bear, and Mimiru went to see Harald, and Mimiru fell off the cliff and was caught by Bear. "Bear, what happens if we die here?" "Calm down, it's just a game." "But...but your hand...it's sweaty, Bear. It's sweaty!"So as long as if you're not into the game at the time of Data Drain. You won't be put into a coma? Well this sure does explain the theory about only being comatose by shock from Data Drain.
Mimiru, scared for her life and overreacting, was slipping into the game, and her mind was creating false stimuli. If she died in that state, she would've created the simulation of death, and would have fallen comatose. It's not what you do to the Player, but what kind of mental state they're in that matters.