Not all metals react with oxygen, water, and acids. Therefore, using these reactions alone may not provide sufficient evidence to establish a complete order of reactivity among all metals.

By observing displacement reactions, we can directly see which metals can displace others from their compounds. This allows us to establish a more accurate order of reactivity among metals.

Displacement reactions provide better evidence about the reactivity of metals because if metal A displaces metal B from its solution, it indicates that metal A is more reactive than metal B.