I know: "the difference between a language and a dialect is an army and a navy." (meaning: there is no difference)
But insisting Scots is a separate language feels like a nationalist thing. As the article mentions, it's not that Scotland doesn't have a real language all its own, Scottish Gaelic. But that would take time to study and master, and it's easier to really dive into your local pronunciation up to a point where no one understands it as English, write it down phonetically, and claim it's a language.
From the article:
"Ye may gang faur an fare waur" apparently meaning: "You may go further and do a lot worse",
or,
"you may go farther and fare worse", if you pronounce it in dialect and just write it down like that.