When will this meme end. Angular is not crazy opinionated. The previous version more so, but it's really open to letting you do things in general ways. You want css scoped to your components? Sure. You want two way data binding? Sure, but wait you want one way binding? You go it. You can use rxjs, or you can avoid it.

There's some general ways to set things up, but it's nice to have a general approach to each project you encounter.

And the biggest thing is Angular wasn't designed to be used by a solo developer working on a side project. It's evolved to allow that, but it was designed with companies in mind. Multiple developers, multiple teams of developers, maybe with little communication to work together on single projects whilst allowing guide rails to keep things headed on the same track, but allowing many ways to move the track in a way that fits your style.

The idea that react is just a "library" (think you mixed up your words there) is absurd when you look at the majority of react in the wild. Using create-react-app, react router, forms library, animations, etc etc, and now look, you just pieced together a bunch of different libraries to form....Angular.