It's the defacto router because it has gone through many iterations, has lots of users, is easy to bring into a React app, and doesn't fight w/ React, it works with it. Plus there are a variety of approaches to declaring routes. [0]
I'm not sure I see how obvious it is that a <Redirect/> is wrong. But that's fine, I take your point that it's not particularly intuitive.
I'm of the opinion that routing, in general, is a function of application state - and I like to manage my application state with Redux - so I will often also mix in connected-react-router [1]. This lets you do navigation w/ an imperative API [2].