For what it’s worth, while I’m perfectly comfortable with HTML and CSS, I prefer JSX + CSS-in-JS. This isn’t because it’s one language versus three. It’s becaus

For what it’s worth, while I’m perfectly comfortable with HTML and CSS, I prefer JSX + CSS-in-JS. This isn’t because it’s one language versus three. It’s because it promotes colocation of related code, and allows a high degree of composability that’s much harder to achieve otherwise. Colocation is great for understanding what a given thing does, and for identifying its dependencies. Composability is great for mapping a domain model to lower level concepts in a coherent way, and for encapsulating dependencies. This is somewhat achievable with separate languages. But it ultimately takes a very similar shape with additional tooling/ceremony and diminished benefits particularly from colocation.