Maybe, but who cares?
I don't think any of the games I have installed right now are rated M. I wouldn't refuse to play a game based on it's rating, but I don't really care for horror themes or gore.
I used to enjoy the Battlefield series, and Star Wars BF2 (the original, not the 2017 version). I would have enjoyed them all the same if they were rated M, mostly because more gore wouldn't have made a difference either way. I'm not there to stare at the details of my fallen foes, I've got still living foes shooting at me to worry about. That might be the difference between tactical shooters and other shooters though.
That said, the main game I play is an old racing sim. I like it because it's as challenging as trying to drive a real car on the limits.
I think I'd be more likely to perceive a gamer as childish if they insist on playing with the difficulty too low to represent an actual challenge, rather than the content of what they play.
For the most part video game violence doesn't bother me, it just holds very little appeal to me.
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Watching liberals try to solve societal problems without a systemic critique/class consciousness is like watching someone in the dark try to flip on the light switch, but they keep turning on the garbage disposal instead.
戦争ではなく戦争と戦う