90% of the time everything is fine. It's the 5% of the time when the unexpected happens that all the precaution and parameters suddenly matter.
That means many are correct being distracted by a cell phone is not a good thing when Instantly something happens. It also means being overweight can also instantly be a problem when something happens.
Knowing your weights and staying within your ratings is just as important as not being distracted or texting while driving.
The catch is you can put your cell phone down and not use it. You can't lose 1000 pounds of cargo quite so easily.
The OP mentions CHP scales. 
Why do you think the enforcement people go to the trouble of  having weigh stations? Part is to protect the infrastructure, part is for taxation and lastly is for safety because an overweight rig is unsafe.
Experience and skill can compensate for a lot of things but it won't compensate for physics. Simply put stopping distances increase significantly with weight and speed.
I'm not suggesting the sky will fall if you're overweight, but I am suggesting that everyone weigh their rigs and know where you stand within your parameters.
Weight is not the non issue some pretend it to be. 
The OP post is about knowing your weights amazingly some of the responses refer to cell phones and distracted driving? There are also drunk drivers and drugged drivers. But that doesn't make it OK to be grossly over your tow ratings