Actually that was how some forms of alcohol used to be made, for example sake in Japan.

> The first sake, kuchikami no sake, (口噛みの酒) or "mouth-chewed sake," was made by people chewing rice, chestnuts, millet, and acorns and spitting the mixture into a tub, where the enzymes from saliva converted the starches to sugar. This sweet mixture was then combined with freshly cooked grain and allowed to naturally ferment.

It might seem like a disgusting practice to contemporary eyes, but it does show the power of human saliva and how one should not discount the process of chewing food. Drinking a liquid vs actively chewing, imbibing the chewed food with your saliva, definitely does not lead to the same thing.