I think you mean that atheism is not a belief in nothing, but rather a lack of belief. People argue that one, not whether or not it's a position taken.
The problem is you're conflating gnostic atheism and agnostic atheism.
Gnostic claims that they know 100% for certain no gods exist - while probably true, this is something we'll never know for certain, much like we don't know 100% for certain that Pokemon don't exist IRL... but we're pretty fucking sure.
Agnostic claims that you simply can't know, and that's the most logically sound position to take, although you can still put forth that it's probably, with overwhelming odds, nonsense.
A person choosing to take no position is functionally the same as someone who will never in their life be introduced to the concept.