A developer who tries to center a row of three buttons on a React Native screen using web instincts reaches for `display: flex` first, only to find every core component already defaults to a column-direction flex container — there is no `display: block` to opt out of, because Flexbox is not one layout option among several in React Native, it is the only layout system available. Getting comfortable with that single system, rather than treating it as CSS Flexbox with a slightly different default, is what turns layout from a source of daily confusion into a fast, predictable tool.
Without a real mental model of how `flexDirection`, `justifyContent`, `alignItems`, and `flex` actually interact, a developer resorts to trial-and-error — nudging a margin here, wrapping an extra `<View>` there — until a layout looks right on one screen size and then breaks silently on another, because the underlying cause was never actually understood, just papered over. This lesson builds that model directly, alongside the `StyleSheet` API that replaces CSS for expressing it.