Node.js is one of the most powerful tools when it comes to creating command-line applications, servers, real-time backends, and all sorts of tools for developing web applications. The beauty of it is that Node.js is JavaScript on the server, which combines nicely with your React frontend for JavaScript everywhere. Even though it's centralized, you'll use it plenty of times for decentralized projects where you just can't get by with the limitations of the Ethereum blockchain. You see, Solidity and Vyper are severely limited: you can't do much besides basic function-based code. At some point or another, you'll have to use a centralized backend for advanced applications such as those that require a dashboard.
At least until decentralized hosting and storage solutions drastically improve, we'll have to get by with...
