I really don't know where you count 3 sentences on the flood myth in the Epic of Gilgamesh - the tablet 11 section is longer than any other and has far more than 3 sentences.
You are again right in saying this article is not about flood myths in general - that's the Deluge (mythology) article. This article's purpose is to show how this flood story diverges from a preferred reading derived from the Atra-Hasis version - a river flood, a certain barge etc. What would be a compare-and-contract is divided into two sections "Sentences copied" and "Material altered", and doesn't include any other versions.
All this article does is present arguments against how the Gilgamesh episode differs from the Atra-Hasis flood story, and its unique reading as presented in the "Alternative translations" section. This page should simply be redirected to the Epic of Gilgamesh.