Glowcat: there's millions of uses for 0 beyond counting apples. And how is "something" not a lack of "nothing"? Wordplay, I know, but without the symmetry of opposites words become useless. If there's no darkness, how can we be sure that light exists, et cetera.
If there are a million uses please give a few that aren't dependent upon a quantity concept. Unsupported assertions do not make for debate.
Furthermore I find your stance on symmetry of words very wrong. Words are meant to be descriptive of our reality so as to communicate concepts. We do not have a word for not-a-pen to describe anything which doesn't fall under the label's current meaning, but we can claim that an object does not fall under the label's umbrella with deductive reasoning and knowledge of what that label represents. In our conversations we never refer to not-pens as if they existed independently of the pen concept.
The issue you encounter when claiming that there can be a not-something is that our entire mind is restricted to the concept of there being something (Space and Time). There is nothing we can compare something to so as to prove it isn't something because the umbrella of concepts that the word 'something' includes is literally everything we can conceive of or encounter. Absolute nothingness is an unreal concept that cannot describe anything without that thing being something -- an inherent contradiction.
EDIT: I should also probably explain more about why your Dark/Light example is wrong as well. Dark does not mean Not-Light, but rather it refers to an absence of light within Space and Time. This falls under the real sense of the word nothing, not the absolute version which I find incoherent.