I’d go further than this and say globally-scoped CSS is fine as long as you’re using a decent naming pattern (e.g. BEM), or @layers.

For me, back in the JQuery days, the problem was always globally-scoped JS/DOM, rather than CSS. The big revolution was simply co-locating/importing styles in JS modules during the compile step, which works surprisingly well even outside of any framework.

Just using vanilla DOM or a small wrapper around web components for connectedCallback/disconnectedCallback logic is refreshingly simple. It’s quite sad that most SSR frameworks don’t allow this sort of approach, and lock you in to a specific front-end library.