Redefine an existing property to an object

I have questions
#1 
const o = { key: '1' };
Object.defineProperty(o, 'key', { value: '2' });
// configurable of `o.key` is true

Object.defineProperty(o, 'newKey', { value: '2' });
// configurable of `o.newKey` is false

I have read the spec of DefineProperty, the result of above code is correct, but It's still confusing for me.
Why not make the configurable of property key to be the default value false? As the document at MDN:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty#description

#2

The ‘key’ property was already defined, so ‘defineProperty’ is modifying the existing definition. The default values are only applied when creating a new property.

This did suprise me the first time I found this out and potentially ‘defineProperty’ was not the best name for that api.

It might be worth suggesting an update on the MDN page to ensure this behaviour is clearer.

#3

Is it possible to revise the DefineProperty to make the definition clearer?