"The importance of DMs sometimes retaining sole authorship"
The thing is though, you aren't demonstrating that. There was nothing wrong with what your player did, you just don't like it an find it awkward because you have to tell them no. Your players don't like it for reasons that frankly, you aren't expressing well, except that they seem to also be upset someone wrote something into your world.
The player did nothing wrong, and there is, from a practical standpoint, nothing stopping you and your other players from embracing his additions, except for the fact that you don't want to. Sure, you don't want to do it, and it is rooted in some instincts I respect, but there is no importance to deciding one way or the other.
Permission? Why did he need permission to write-up something and present it to you? And frankly, if you had liked his ideas, since you are the "sole author" then you would have implemented them whether the other players liked them or not.
I mean, they guy didn't just sit at the table and star telling you who these NPCs were right? He probably handed you a document of names and background sketches before or after the game? Maybe an e-mail sent to the whole group? This is the type of phrasing that makes it feel like you are upset, that he somehow crossed a line.
And, by horrible, I was worried that he had written characters along the lines of "a secret runaway princess deeply in love with my character." That sort of thing I can see upsetting people. But if they are perfectly fine characters, just not your characters, then what he did doesn't seem that bad.
See, this is the sort of detail that clicks things into place. This isn't just a player making NPCs, this is a former DM pushing his NPCs into a new game. A game partially or fully made up of people who quit his last campaign in part because of how he pushed his NPCs, giving a repeated pattern.
Heck, if you'd led with that I wouldn't have even bothered with most of my response, because this isn't a player getting inspired, this is another DM seeming like he is trying to muscle into your turf. Of course this is going to raise hackles, especially with a group of players who quit his game.
Yeah, no, now this all makes a lot more sense. If he wasn't the former DM of the players, or a DM with a pattern of heavily pushing his NPCs, then I'm sure this entire issue would be perceived very differently by your group. You might still be annoyed, but I'm sure the other players reactions are in large part because it feels like him repeating what they left his game to avoid.
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Unless the player is asked to narrate the outcome. Which some DMs do.
Again, I'm not trying to say that one way or the other is preferable for all given tables, but if your argument is that the DM must have authority, and you support that by things that only the DM can do... the fact that none of those things are actually limited to only the DM undermines that point.
The players can make rulings, if the group agrees.
The players can narrate the outcome of their actions, if the group agrees.
So neither of those things prove that a DM is necessary, only that some people prefer to have them.
And yet the Toxic players are integrally tied to the in-game role of the DM, and completely productive examples?
This is why we keep saying that focusing only on bad-faith player arguments, a thing people keep doing over and over, and that you defended doing, are not helpful rebuttals to our position.
Because as soon as we bring up bad-faith DMs, it is irrelevant, inappropriate, and not productive.
When discussing two sides, if you are allowed to paint one in as negative a light as you wish, but the the other can never be painted in a negative light, the argument is skewed.
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"Not in his favor" is a funny way of saying that he accused me of lying about what he said, and he literally said what I claimed, in the post I was quoting, and the material I was talking about in that post he called a lie was about that post I was quoting.
I mean. I'm trying real hard to be reasonable here, but this is fairly black and white. I did not go and grab an unrelated post to defend myself from the accusations of me lying, I grabbed the post originaiting the quote he called a lie, and showed step by step that he said exactly what I claimed he said.
So, when he accused me of lying about what he said, he didn't want me to focus on the part I was quoting, you know, the thing where I was being accused of lying, but he wanted me to take into account every single thing he has said over the entire 50 pages.
Why? Because he contradicted himself and his other posts show that what I quoted wasn't true?
Well, that'd be great for me, wouldn't it?
There is no perspective here. There is no debate. Oofta said I lied, and that he never said what I was talking about.
I quoted him, word for word, highlighting it. He said those things. That means I didn't lie, because I was responding to those things.
You know what the funniest part is? I'm sure people noticed that I've been responding to Oofta separate from everyone else, not in these big multi-quotes? You wanna know why? Because in the last thread, he complained it was hard to find my responses when his were part of everyone else's. So I changed my posting style, specifically to accommodate him. And now I'm being called a liar, because he didn't want to confront my arguments.