Many sites claim that bedding and underwear should be thrown away for sanitary reasons every few years (the exact recommendation varies between sites and clothing/bedding type).
This, regardless of the laundry routine they endure. So for example, even if you wash your underwear at 60°C with bleach every day, they should allegedly be thrown in the garbage every year for sanitary reasons.
How does this make sense? Why does the item's age matter? Isn't a 5-year old item (pillow/underwear/duvet/etc) as good as new, hygienically speaking, after being washed with a detergent at 60°C? Do you mean to tell me things get "too contaminated" over time, to the point where they are a "sanitary lost cause" and must be thrown away and replaced?
Note that I'm only talking about the hygienic perspective. For the sake of this discussion let's ignore things like loss of functionality, comfort, aesthetics, etc.