Well....yes....rods and reels wear out, just like anything else. However the wear is usually over a long period of time and is usually pretty evident.
Rods - typically the guides get loose, damaged, cracked, lose their inserts, etc. Easily repaired by a DIY with a little practice, or their are many repair shops. Otherwise rod blanks are pretty much good unless the rod has been stepped on or overstressed and then cracks are evident.
Reels - Wear items....lots of small moving parts in a harsh enviroment.....need to be cleaned and lubed regularly. Expect 5-10 seasons from a quality reel with decent maintenance, some people get a lot longer.
I've actually had more damage to rods and reels from transporting to and from boat than I've actually had problems fishing.
Used rods and reels - I love yard sales !!!!! I have bought many quality rigs at near nothing prices over the years and rarely been disapointed. A good inspection is needed of course but no problems.
Used equip from a tackle shop? Depends on the price and history of the merchandise and your relationship with the shop. Used equipment can be a real good deal.
I have even gone so far as to buy good rods with questionabe reels or the reverse and then replace the bad item with new, you still come out ahead financially.
Hope this helps