* History: on modern browsers this is ~5 lines of code? Pushing URLs with pushState, triggering PopState events, and binding a popstate handler to trigger render changes.
* Route parsing: just use pathToRegexp. Yes, it's a dep, but it's an easy, well-understood one that does one simple thing you can get your head around. Or: don't use route paths with parameters at all (it's overkill for a lot of applications) and just use a trivial switch statement.
* Nested routes: why bother? The routes we're talking about are totally artificial. Having a formal, declarative route system in the first place is already a lot of "engineering". Just define your routes so they don't do that.
My argument is that the hand-hacked system that does this will be approximately as capable, future-proof, reliable and performant as the first production system anyone builds with react-router will be, the learning curve is shorter, the code you're building won't have APIs shift out from under it, and the final system will be trivial to port to react-router once that library stabilizes, if you ever wanted to bother doing that.
