Why do headliners fall?

Lets clear all the myths. I have heard. Its because the vehicle was smoked in, It got wet, They put in a windshield and ever since then..... It was detailed and after it fell.... bla bla bla. I have seen many a good company and technician wrongfully blamed for headliner failure. The truth is HEAT! Its Heat that destroys the foam and glue backing. In other parts of the united states It take forever if the headliner ever falls or de laminates, Florida, Texas and Southern California there is extreme heat and many headliners fail due to it. If your headliner fell after someone worked on your car its most likely because it was probably being held by trim only that was removed and it fell but it was on its way out and that just finished it off, but that is why, no other reason. I worked at a shop one time that re did all the headliners from a major company that had a lot of claims of falling headliners but were never there fault. But these big company s just flip the bill in fear of people being upset. Its completely wrong because this makes cost go up from people being free loaders. Okay ill stop my rant.