Most people misunderstand the various stages of digestion, and think that there is no point consuming alkaline substances when the stomach is acidic. If this were truly the case then there would be no use to consuming alkaline foods (greens, vegetables, fruits, nuts, seeds, salads etc.) and we would only need to consume acid foods (sugar, chocolate, gluten, chips, pizza, soda etc.).
When you consume alkaline forming foods and drinks, the stomach processes them, and prepares them for the next phase of digestion after the stomach (the duodenum) which requires them to have an ALKALINE pH far easier than when we consume acid-forming substances. The more alkaline you eat and drink, the easier the digestive process. I explain more here, if you need more detail