Hehehehehe, the line.
This type of line may be the hardest thing for humanity to ever solve, you could argue even impossible. Building rockets and flying to the moon is trivial in comparison, because once you figure out the precise engineering required, it works, definitively, no matter what, forever. People who enjoy crossing the line will continue tweaking their responses to get closer and closer to whatever line may exist because they want the maximum amount of crossing that doesn't get them banned. At the same time, global culture and opinion is constantly changing, putting pressure on us in different directions and shifting slightly where the line has to be.
This is why the terms of service must be as precise as _possible_, but still with plenty of ambiguity, so that we don't have to change them every 90 seconds to add minuscule tweaks and examples of precise language, which then of course users would slightly tweak their behavior to avoid.
At the same time as all that, the line is subjectively dead simple. Don't be a jerk. If you are, your content is liable to be deleted. That's it.
I do agree that more consistency will always be better. Unfortunately, us moderators also have the curse of being human, so we cannot perfect the line we draw with the same precision as those perfectly machined rockets :)