Link to Pew Research Center report, "Luxury or Necessity? The Public Makes a U-Turn".
Excerpt: No longer do substantial majorities of the public say a microwave oven, a television set or even home air conditioning is a necessity. Instead, nearly half or more now see each of these items as a luxury. Similarly, the proportion that considers a dishwasher or a clothes dryer to be essential has dropped sharply since 2006.
With these facts in mind, collection development librarians are encouraged to evaluate the 643.6 Dewey classification.
With the emphasis on maintenance.