Look, if you dislike it. That is you.
Please stop telling me what I like and dislike. I have told you repeatedly that I sometimes play games very much like the ones you're talking about.
It's not about liking or disliking. It's about recognizing what is happening at the table, and what the design choices allow to happen at the table.
But I think this sort of ability by the GM to do strong characterization of NPCs is vital for the players engaging with the setting. That is what makes it interesting when they march up to a gambling hall with aims of brow beating the proprietor: maybe they know about the guy and have heard he is a tough cookie, maybe they haven't heard anything and it is a surprise, maybe they gathered information and learned he is stubborn but also found out what kinds of things impress him. Real people are going to sometimes have hard lines, and I think these kinds of moments, where PCs are negotiating or coming into conflict with other characters are greatly enhanced if there are sometimes hard lines in place that the players have to work with or around. Part of having agency is dealing with the world in front of you.
You're focusing on the wrong thing. No one is saying that the GM can't or shouldn't give his NPCs strong traits. What we're saying is that those traits impact how the play of the game can function and so must be considered.
In and of itself, it's not really a problem to make a guard totally loyal to their liege. Indeed, such people are likely to exist. However, the way that this is presented in play, how it impacts the interactions of the players with this NPC, how it interacts with other setting elements, and
most importantly how it interacts with other decisions that the GM has made... all of that matters.
It's my contention that the GM should be very aware of these things.
It doesn't have to be secret. It simply depends on the situation. A lot of guards who have traits like this, those will be discoverable facts in the setting. But it might not be. It depends on the NPC. You are trying to give the GM the greatest freedom possible to invent characters. And there are other principles in play. The GM isn't expected to just take this and use it to be a jerk to the players. If that is a problem, it is a problem. But I find it very unpleasant to play systems where the problem of bad GMing is solved by limiting what good GMs can do. And I am not saying such systems are bad. I am sure people like them. But try to understand some of us see value in this approach
I don't think that the GM considering the play implications of NPCs he designs to be all that restrictive on his creativity.
And it's not about being a jerk. Might someone willfully block players? Yes, of course... that person's a poor GM or is GMing poorly in that moment, at least. I'm more concerned with those who create these situations without realizing it. And given the lack of understanding about this topic in this thread, I think that's a relevant concern.
Now, again... if what you're talking about is what you prefer, then that's perfectly fine. But from my view, it's placing the GM's freedom above that of the players, and the setting above the game.
Interacting with NPCs is part of the game
Yes, and to what purpose?
Someone recently asked me, is the setting there to serve the game, or is the game there to serve the setting? That seems valid here.
Player agency within the setting is the main antidote to railroading, so it seems odd that some of the most strident anti-railroaders are also eager players of systems that intentionally deny some of that agency.
Looked at from a different angle it's almost like low-grade system-based railroading instead of DM railroading. I fail to see how one is any better than the other.
Sure, I get that you fail to see it. But do you think people who are saying that they enjoy such games are lying to you? Or are they just wrong about what they enjoy?
Maybe consider what they're saying and accept that it's true for them, and then maybe try to imagine why it would be so.
If you can't, then sure, stop worrying about it and ask again in the next thread.