Due to premature wear and stress. The following video is of a folding kayak with multiple wear points after one year:

https://www.youtube.com/watch?app=desktop&v=eztYecW6sBE&t=132s&pp=ygUNRm9sZGluZyBrYXlhaw%3D%3D

I recommend the packraft route. They fold smaller, weigh less, can carry more weight, can go through most classes of water. Packrafts from higher end brands have an estimated life expectancy of at least ten years.The only advantage to folding I see is forward speed with folding kayaks.