I have worked on ultra-violent games but never did research on what actual killings looked like as referenced in the article. As the one quote said, context is important as well as how close something gets to realistic looking. That embedded Mortal Kombat trailer was pretty unrealistic looking IMO, the physics was cartoon like and several what would be real life death blows were not death blows until the fight was over. I was pretty disgusted by these sorts of things when Mortal Kombat came out when I was a child and didn't get the appeal of it so maybe I got inured to cartoon violence by exposure. OTOH, Breaking Bad had a few death scenes similar to one of those, and aired on prime time basic cable.
For one game I worked on, I was instructed to get blood splatters for cuts and slicing off of body parts (in a cartoon character world) like the movie 300 which were over the top and very obviously particle effects (the producer loved referencing current popular culture...). It never occurred to me to go looking for what blood spurts look like in real life, as I was given an order for a style.
Most of the games I have worked on were not realistic looking, though I remember doing internal tiger team testing for Warcraft 3 and there was one mission where you have to kill villagers. These characters are tiny and cartoon like but the voices of them suffering in this made me feel so bad and similar to stuff happening the real world I thought we should take the mission out of the game - I think they toned it down a bit but it was in the final version.
This is kind of similar to the mission in Call of Duty series where one has to participate in the slaughter of civilians in an airport - I didn't like that one either.
I still have trouble watching some of the fight scenes in TV/film/wrestling when they look too real or wince especially with blades, even though it's obviously stunts with props and probably CGI for the most gruesome bits - I have retained sensitivity to realistic violence.