So reading this article made me have a bit of an epiphany: What is being described isn't CSS-in-JS. Instead, this is style properties in JS.
This is the equivalent of inline styles. We don't call it "inline CSS" because it isn't CSS. Nothing cascades with inline styles, just as they don't with "CSS-in-JS". And you don't have to worry about specificity with either implementation.
In other words - all the things that make CSS the powerful language it is are stripped away to just a listing of arbitrary properties.
So, CSS-in-JS, do yourself a favor and stop calling it that, because what you are coding is nothing even remotely close to CSS.
This is the equivalent of inline styles. We don't call it "inline CSS" because it isn't CSS. Nothing cascades with inline styles, just as they don't with "CSS-in-JS". And you don't have to worry about specificity with either implementation.
In other words - all the things that make CSS the powerful language it is are stripped away to just a listing of arbitrary properties.
So, CSS-in-JS, do yourself a favor and stop calling it that, because what you are coding is nothing even remotely close to CSS.