The gap between a component library and a working design system is larger than it looks. Components in Figma need to match components in code. Tokens need to be real rather than named. Teams need to trust the system enough to use it instead of working around it. Implementation is where the theory meets the constraint, and the constraint is usually cultural rather than technical. Getting a team to stop their own patterns and use a shared one requires the shared one to be demonstrably better.
Design system branching in Figma is how you keep the source stable while that trust is being built. Design debt as a performance indicator is usually what makes the case for starting.