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 lang

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.