I am not convinced that, when using a framework (React, etc), the best way to enforce consistent UI is via the framework.

A button should be styled independent of the framework. That's how you will get consistency. Same with every other non-component element.

The use of the component framework should be to consistently style non-primitive style elements (all the standard HTML elements).

What value is there in using React/whatever in styling buttons, links, paragraphs, headings, various inputs, etc? Today, in 2026, even menus, tabs, etc are done with nothing more than primitive elements; what value does React bring to the consistency of menus that you don't already have?