Theyre made of cheap "pleather" material that flakes apart with time. I have some expensive headphones that have done the same. You can just buy replacement ear pads and slip them on like a fitted bed sheet.

Just the pressure of the frame is enough to cause this. It's a stress point for the material

These kind of pads are not really made to least long. Normally you can replace them

Round things still are subject to friction.

That's like saying "Water is soft and conforming, I'm unsure how it could carve a canyon."

The fabric is thin and wears out over time from taking them on and off. Mine eventually just crumbled into tiny flakes everywhere