Why would you add a buffer to a reaction if all of the solutions are already neutral (pH 7) ?

A buffer is added to the solution so that it can resist pH change.

Explanation:

An aqueous solution which is a mixture of a weak acid with its conjugate alkali, or vice versa is referred to as a buffer solution or pH buffer. It can resist a pH change upon addition of basic or acidic components. It doesn't show a drastic pH change when a strong alkali or acid is added to it. So, buffer is added to already neutral solution so that the pH change is kept minimum.