USB/Flash memory is not an archival storage medium. It is far to volatile, so as long as you are not using USB sticks as an long term archive for precious, irreplaceable documents/data, it shouldnt be a big deal to you.
Flash memory will self-erase if left idle/unplugged for a long enough time.
Mechanical hard drives can be archival, but you cant just load them up with data and shove them in a closet.. They need to be hooked back up and spun up every month or so, to keep lube moved around and keep platters and arms freely movable.