There was no advice given.
There are literally hundreds of threads on this forum discussing people having Cornish Cross break legs, have heart attacks, and die with fluid in their abdomens.Yes it is discussed quite a bit but very few authoritative solutions are provided. The information is generally amatuerish. Many of the people on here growing them have 10%+ losses And that is sad because so much of this needless loss of birds could be prevented.- most of these things can be prevented, Very true
but giving them free access to food is generally a bad idea. These birds are bred to have voracious appetites yes and also the ability to utilize what they eat. The method of preventing many of the problems you attribute to "eating themselves to death" (preposterous) are actually caused by bad light management and inadequate nutrition.
If you have resources stating otherwise, provide references.