What is the use of weight and style property when declaring custom fonts in pubspec?

Question

To understand my question, we need to follow the example below which from the official flutter documentation:

flutter:
  fonts:
    - family: Raleway
      fonts:
        - asset: fonts/Raleway-Regular.ttf
        - asset: fonts/Raleway-Italic.ttf
          style: italic
    - family: RobotoMono
      fonts:
        - asset: fonts/RobotoMono-Regular.ttf
        - asset: fonts/RobotoMono-Bold.ttf
          weight: 700

As you know this is how we declare font in Flutter and we know that we have Raleway-Regular.ttf, Raleway-Italic.ttf, RobotoMono-Regular.ttf and RobotoMono-Bold.ttf inside the fonts directory at the root of our project.

So my question is why do we need to set the weight property of the RobotoMono-Bold.ttf to 700, when by default RobotoMono-Bold.ttf has FontWeight.w700

The documentation quotes

Note that defining the weight property does not override the actual weight of the font. You would not be able to access RobotoMono-Bold with FontWeight.w100, even if its weight was set to 100.

As per the documentation if defining the weight property does not override the actual weight of the font, then why the weight property exist? Same goes for the style property as well.