JCtomas -you are correct that everyone has different staples in their pantry! But I believe that EYB as recognized correctly that a line must be drawn somewhere to identify the most important ingredients in a recipe.
Jane is correct - that the information available on this website (including the table of store-cupboard ingredients) will help to clarify what is meant by the "store-cupboard" description. It also explains that certain items are never indexed - salt, baking powder, etc. Other items are sometimes not indexed if the quantity is small but are listed if a larger amount is called for - for example, a tablespoon of flour in a sauce would not be listed, but three cups in a bread recipe would be shown. The ingredient "Store-cupboard ingredients" itself is not supposed to be used unless the aggregate quantity in the recipe is significant.
One of the most important things to remember is the list of ingredients is what powers the search engine. You can't search or include/exlude on store-cupboard ingredients .. nor would you be likely to want to do so.
I have found in the indexing that I've done that the "store-cupboard" designation tends to be most often used in baked goods and occasionally in dressings. Otherwise, any store-cupboard ingredients called for are so small in relation to the recipe as a whole that the designation isn't often used.