All you really need is a service with an app model that you inject anywhere you need it. That is basically your state. There is no ‘management’, like with Redux reducers, you just mutate the model directly. For all but a few of very specific use cases, where data flow is much more complex than normal API calls, this completely works, bug free, and is way more practical.

I have noticed on the project I work on at my job that people really overuse observables, I suspect because it feels more sophisticated, and they get hyper-aware of asynchronicity. The trouble is observables are not free, efficiency-wise, especially on forms, where they can fire a lot, and can bog down your application. Plus, they require a lot of confusing programmatic plumbing, and make the whole application feel twice as complex. Over-complexity is bad engineering. I think it is easy to forget that, with the judicious use change detection, template syntax works with even large amounts of asynchronous data just fine, and is plenty efficient.