It can happen. My old backpack's straps had become like that, and I hadn't noticed at all. I used the backpack every week two or three times for grocery shopping, for more than a decade. Then once, for whatever reason, I noted the straps felt kind of strange, rough. I grabbed one with my fingers and gave it a yank. I could tear it like cardboard. So, I had carried sometimes several kilograms of stuff relying on straps I could easily tear with my fingers alone.