> 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.
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.
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.