Both approaches are valid and applicable in different circumstances. To extend your example further, you often end up needing to do:

  function MySubComponent({ disabled }: { disabled: Signal<boolean> }) {
    // ...
  }  

  function MyComponent({ disabled }: { disabled: Signal<boolean> }) {
    return <MySubComponent disabled={disabled} />
  }

passing the value on and on as you go down a component chain. Context lets you avoid all that.

Where signals offer an important benefit is in localizing re-rendering. If you use context with regular, non-signal values the entire VDOM tree has to be re-rendered when the context value changes (because there's no way to know what code depends on its value). With signals you can change the value of a signal in the context without changing the context itself, meaning that the only part of the VDOM tree that gets re-rendered is the one using the signal.

With performance considerations out of the way context becomes a really interesting way to provide component composition without having to specify the same props over and over as you make your way down a chain.