The break away chain part is simple, maybe not necessary if you're just towing around your level yard.
But the uncontrolled 3 pt rise can happen like Piston mentioned with a dump trailer, when you tilt the bed to dump, before the load slides out it puts a substantial (with my 5 ton dump it's pretty extreme) upward force on the tongue. That would allow the 3 pt arms to rise out of control, I'm not sure what damage if any that would do, but it is undesirable to have that kind of uncontrollable movement.
That same negative tongue weight or upwards force can also occur with any type trailer, while braking down hill or backing up hill, even with an otherwise well balanced load in the trailer.
I don't know why the manufacturers of these hitches don't warn of and provide an attachment point for a limiter chain.
I recently saw one advertised, with weight brackets and colors available, also a rolling stand to store it on with the suitcase weights and all, all the bells and whistles. But no break away chain loops or limiter chain option.
So I wrote them a nice email complimenting them on their product line but strongly recommended they incorporate the aforementioned attachment points.
never heard back from them so I don't know if they appreciated that critique or not.
JB