It's clearly evident there's a disconnect between combat focused players who like to make things go boom because "it's a computer game and that's what you do", and more deeply invested, but often less combat-skilled, less combat-prepared players, who often have a lot to lose, and often take the shallow violence of the other group deeply to heart.
Group 1 doesn't really understand Group 2. To them, they're anoraks unfathomably building train sets in no man's land. To them it's amusing to see these strange people get uptight over a computer game. Group 1 are just playing Elite as they have played games all their lives, from Space Invaders to GTA to Skyrim: kill stuff. They're the people who can't stop themselves executing the innkeeper or the quest giver. Action games, to them, are about letting off steam by blowing stuff up. They would probably get bored with shooting Group 2 but...
Group 2 cannot let it go that someone would be mean to them in a computer game. They dress it up every which way, but bottom line they are apoplectic that people are trying to turn their carefully managed trainset into a free-for-all. They say "hey, you killed me without roleplay!" Roleplay? Group 1 don't have any concept of that. To them, games are nothing to do with real life, there are no "real" feelings or immersion involved, it's just a shallow pastime (in some ways, it can be a healthier outlook). To Group 2, games are not just an escape from real life, but also an extension of real life. So when they get summarily killed for not particular reason, they don't feel like they got beat in a game and move on, they feel BULLIED.
I say that as someone who is probably closer to being a member of Group 2 than Group 1. Obviously, each of those is a distillation and few people will fit into one group perfectly, but I think those are the two prevailing mindsets that cause this issue in the community. As far as I'm concerned, that's the answer to WHY? and it's also why these constant threads do nothing but exacerbate it, IMO.