I have a lot of fairly old velcro around and it still retains it ability. On occasion I have had to clean out gak from the the hard, hooked plastic portion of the closure (but hey! that's just like dryer lint for firestarter, right?) After cleaning , it went right back to functioning well.
Bottom line, I don't think it is a big issue. In fact, maybe the dryer lint stored in velcro patches, combined with ear wax, would provide a dandy firestarter. We all probably have extra lint in our belly buttons, as well.
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Geezer in Chief