They also have Worn Wear, where they take back used products and sell them at a discount. The fact that there are so many used items they can sell in good condition is evidence that their products hold up pretty well.

Something seeming to be common sense isn't the same as 7scientific investigation. Lots of things seem intuitively true but aren't, and foundational research paves the way for more complex studies. You can't base a study on something that seems about right, but you can base it on previously published research that supports your premise.