Expo React Native - How come returning null on App.js initialization function is good behaviour?

This is mainly a comprehension problem:

Considering the following expo docs, which aren't explaining what is going on under the hood,

import { useFonts } from 'expo-font';
import * as SplashScreen from 'expo-splash-screen';

SplashScreen.preventAutoHideAsync();

export default function App() {
  const [fontsLoaded] = useFonts({
     'Inter-Black': require('./assets/fonts/Inter-Black.otf'),
  });

  const onLayoutRootView = useCallback(async () => {
    if (fontsLoaded) {
       await SplashScreen.hideAsync();
    }
  }, [fontsLoaded]);

  if (!fontsLoaded) {
    return null;
  }

  return (
    // Your app tree there.
  );
}

What is going on here from my understanding is that you prevent the splashscreen from going away while you retrieve certain assets, like fonts.

When you do have your assets, you make the splashscreen go away and you launch your app by returning your components' tree.

The part I don't understand is why is it ok to return null if the fonts don't get loaded?

Since it is the initialization function, my mind want to think that if you return null to it, your app doesn't start and the user will be left wondering why...

Is there an explanation, a logic behind the hood actually refreshing something to recheck until it is ok and the assets are indeed loaded or something I don't know?

I know I have the case of my app not starting correctly every time right now and I'm wondering if this "return null" on the App.js function could be the culprit.