I think the selling point for devcards/React storybook et al. is that of a live/visual styleguide of UI components. Imo its raison d'etre is that it promotes a UI component centric methodology for developing web apps, whereby designers and developers can develop UI components in isolation away from the cognitive noise of how those components come together in a single monolithic app. That's the innovation here, if you can call it that, ... the state travelling stuff is an implementation detail.