The whole point of shadcn/ui is that it’s customisable (that’s why the components are copied into your app as opposed to installed from a central npm package).
The reason why customizing has some mild disincentive is because as you install more components, all the other new components won't be aware of your changes. Otherwise it's a great start for a custom design system.
That's funny. I thought ShadCN was LLM generated when I saw this thread and clicked the link. I didn't realize it was the ancestor of all the other stuff.
We initially looked into using shadcn/radix - but it's quite bloated. Maybe even warranted with all the a11y accommodations - even the official W3C ARIA examples are not straightforward (most of the time).
This is made easier with the /create UI: https://ui.shadcn.com/create
People use it like a design system, but it’s more like a design system for design systems.