I mean, it's necessary, at some point, to see a full system that uses all the tools for delivering a real application. But, it is definitely a lot of concepts to grok at once. I actually found it most useful to see tutorials that started without even using React, and built up from first principles to what React does (given that React is conceptually very simple, this isn't so crazy...a toy version of React can be built in an hour or so, so it's perfect for a video or article; much of the complexity in React is in making it fast rather than in making it work). But, that may not be a necessary first step for people who have more frontend or reactive programming experience than I have.