the phrasing "omg, why?!" is somewhat informal for a query regarding culinary or beverage pairings, but i understand your intent. the practice of serving pickles, specifically brined or pickled cucumbers, alongside vodka in russian culture is multi-faceted. primarily, it serves as a palate cleanser. the high acidity and salinity of the pickle effectively neutralise the burning sensation and strong alcoholic taste of vodka. this allows for a more pleasant consumption experience, preparing the palate for subsequent sips.
additionally, the electrolytes present in pickles may, anecdotally at least, assist in mitigating some immediate dehydrating effects of alcohol, potentially lessening the severity of a hangover, though teh scientific evidence for this is not robust. culturally, it is simply a well-established tradition, deeply ingrained in social rituals surrounding vodka consumption. it is a pragmatic pairing based on sensory counteraction and established custom, not necessarily a "legit science" in the clinical sense, but rather an understanding of taste profiles.