Oh, I don't know. Could be the endless complaints about adding in a cook to a kitchen.
Or maybe the endless complaints about players trying to add things to the setting.
I mean, if improvisation is a critical skill for a sandbox and for simulation, then, suddenly, all those meta-game style mechanics are back on the table. What's the difference between "improvising" a cook in the kitchen and adding a cook to the kitchen because of a failed skill roll?
It's not about a "gotcha" moment. It's about the fact that the goalposts have been on roller skates all the way along.
I don't add things to the fiction based on what I consider unrelated actions taken by the characters unless there's a logical chain of events. I don't add things simply to add drama or excitement during the session. That doesn't mean I don't regularly have to improvise when things go an unexpected direction like they frequently do.
The cook is a mechanism, fail forward, done in order to change the ongoing narrative in a way the GM thinks will suit their needs. I don't do that, once the session starts I'm the referee.
That's different from having to consider things like balance, but it's a question of whether or not there are 3 or 4 thugs accompanying the pirate captain, not whether or not the pirate captain and his thugs are at the Tilted Tavern where a fight is likely to breakout.
I may make tiny tweaks here and there, I don't modify scenarios in order to "move the game forward" or because "failure is boring". If the goalposts are shifting for you, I suggest you see an eye doctor.