Can someone explain to me why someone would choose Redux over something like MobX ?

I feel like implements an action for each modification of state (or group of modifications) requires a lot of boilerplate code. In MobX, you treat your data tree as a separate entity, and simply modify it. The UI is automatically updated whenever it needs to.

Mobx isn't bad performance-wise, I think, since it only re-renders the components that are listening to the modified variables when a modification occurs.

The only advantage I see is being able to rewind the state store, which can be quite cool when debugging.

I have done some medium-sized application (only games), and I don't think I've run into any performance or readability problem with MobX. I've never done web apps with a team, though, but I don't think Redux would specially make it easier to work with other programmers.