The danger is created in the first place by normalization of speeding.
I am aware that, technically, if I'd drive by traffic at any given time, accidents will be less likely. But this danger of variable speed is not created by me moving too slow, it's because of others moving too fast, because speeding is normalized in the first place, which introduces the problem that wouldn't otherwise be there. The lane speed should be within bounds of speed limit, the rest is not and should never be my problem or fault.
Now, don't get me wrong, if my actions can prevent an actually imminent accident (such as speeding up to let someone return to lane before reverse traffic traps them) - of course I will. But for regular driving, I strictly adhere to the rules and regulations. If this gets someone who breaks the rules in an accident - that's on them, maybe it'll teach them a lesson.
I'm pretty sure those who have set it at 60mph have calculations you didn't consider.
Maybe there are places on the road where someone may suddenly appear, be it human or a wild animal? Maybe the road can get slippery? Maybe the cars going above 60mph create too much noise in the neighborhood? There are many more reasons one could set a road at that, and many may not even come to your mind.
And no, this is almost certainly not about tickets. If it is - screw them and follow the rule!