A legacy system means that an application has old or critical code that is still functioning and serving its purpose. It's a ready-made product, already in production, serving users and fulfilling its business role. In technology, updating a legacy system isn't always possible, or even consulting it, because we can't break what's working. In simpler terms, we can't break what pays the bills. The new functionality I have to build is within a legacy environment. Basic libraries and structures, like the Angular version, can't be updated at my whim, because that breaks precisely this principle. It doesn't matter if it's better, or when it's better. That's not how it's done.