I feel like Turing completeness has always been set as the boundary of programming language if there's any boundary at all. That's what people has been using to not include HTML as programming language for example. Or to include MTG as one.
I think it's a pretty recent thing. Turing completeness is neither a sufficient nor a required property.
HTML is not a programming language, it's a markup language - it's in the name, and it's the way it is used (it's not used to describe any kind of computation, it's straight up data that is parsed by algorithms).
Neither is PowerPoint, or game of life a programming language even though both are Turing complete.
I think it's a pretty recent thing. Turing completeness is neither a sufficient nor a required property.
HTML is not a programming language, it's a markup language - it's in the name, and it's the way it is used (it's not used to describe any kind of computation, it's straight up data that is parsed by algorithms).
Neither is PowerPoint, or game of life a programming language even though both are Turing complete.