As has already been pointed out if a added point of interest is visible on the "standard" map depends on many factors and should never control if you should add a feature or not.
What is confusing you in adding the stores is that iD has two slightly different ways of supporting adding features, on the one hand it has "presets" for different types of facilities (restaurants, electronics stores etc), on the other hand it has a predifined list of names and and corresponding feature types to avoid typos and different tagging for shops of the same chain.
Good example is "Best Buy": if you enter it as a name or search for it, iD will automatically use the preset predefined entry for electronics store of the Best Buy chain, chain of stores, that is what the list entry "Best Buy - Electronics Store" is indicating. If you check you will see that the name files is actually only set to "Best Buy" as it should be.