[namdnay]

> The leftover parts could be identified by crowdsourced databases as nonimportant

In a low-margin business such as home appliances, I'm willing to bet every single part's cost/benefit ratio is carefully examined by experts before being added.

[corin_]

There's always going to be some parts that are just the difference between good and better (or perhaps bad and less bad) rather than working and non-working. For example in an iron that can spray water there could be a piece that breaks up the water into a wider spray rather than a solid squirt.