You won't be reinventing the wheel for things like global state management and javascript routers. I promise. These libraries are huge solutions to problems that may or may not be huge - and in most of the cases I've seen, YAGNI.

The concept of maintaining application state is nothing specific to SPA's. What is new is the idea that every application must have a global data store where all state is saved. This is a trend and not always necessarily a best practice.

This isn't a matter of reinventing the wheel, it's a matter of using an oversized solution for an undersized problem.