Because this is a thread about American exceptionalism, and the name distinction between a whole continent and a specific country can be attributed to several things such as the Monroe Doctrine and Manifest Destiny, and even that history of why Americans took the name of the continent for themselves (going back to their expansionist nature and as a warning to Europe to stop interference) is relevant to the topic.
I'm perfectly aware Latin Americans aren't ignorant on this, in fact that's my whole point. You might still be though, considering you took offense to someone making a simple correction to your distinction between "North America" as a continent vs America, and subsequent correction where in fact, in context, all parts are actually called the same. The tangent started with the argument that people would identify as Americans in LA countries, which I did not make.
And I'm still not sure why are you so offended by simple corrections. Some people prefer to be accurate about it. This might be an English speaking American forum after all, but people from every country and different backgrounds participate in it just the same, offering different perspectives that you are somehow irritated by.