Yes. You seem to be treating lacks a grounding in logic or versimilitude as entailing is illogical or immersion breaking.
But that is a mistake.
What?
Illogical is literally defined as lacking a grounding in logic.
Suppose, in the course of GMing a session of D&D, I describe a room to the players. I don't mention its flooring, because I haven't thought about it. A player asks whether the floor is timber, or flagged, or tiled, or . . .
Now, in the fiction there is an answer to that question. The floor must be something-or-other. So, as GM, I have to make something up. It may well be that neither logic nor verisimilitude dictate an answer. That doesn't mean that when I make up an answer, that answer will be illogical or immersion-breaking.
I dont have the personal connections, alignment and resources of literally every NPC on the planet mapped out do I?
Like I have repeatedly said, I make the decisions on what the NPC connected to the victim does based on likely resources, alignment, connections, motivation (and 'you killed my daughter' is a pretty strong motivation) etc.
Mafia dudes. Lords, High Priests, connected people etc tend to have personal connections, a vested interest in dealing with troublemakers, murders and law breakers, resources... or all of the above.
There is a distinction here between flat out murder-hobism (the PCs suddenly and for nothing more than a trivial reason murder a Tavern keeper, and burn down the tavern) and the PCs killing (say) a NPC for genuine in game logical reasons (he's a BBEG, he's attacked them, they're a bunch of hired killers and he was the target in question etc).
Both of those things are likely to have in game real world consequences, but only the former is an example of Players being douchebags.
And I dont brook players being douchebags at my table. They get a stern warning and a 'No' the first time, plus a statement of what I expect from them, and then (if that doesnt work) get publicly tracked down and hung (or similar) to remove that PC from the game (and a pointing to the nearest door for the player in question, to remove the player from the game) if they do it again.