Stateless functions still deal with state, they just don't hold onto it. Without state to mutate, a so-called stateless function doesn't do anything.

In declarative languages, your state is the sum of everything you've declared. You don't query results out of thin air. Computational results logically conclude from everything you set up.

HTML ""has state"", as in it has a DOM, but it doesn't do anything with it. You don't mutate the DOM after it's built, or query the DOM to compute results that weren't trivially evident from the state you declared.

You can do those things with JavaScript. But all that proves is JavaScript is a programming language, and HTML is just a data format it can interact with.