Folks like to quote the joke, attributed to Max Weinreich, that “a language is a dialect with an army and a navy”. They typically do so when trying to cast aspersions on the very notion of languages and dialects. As my pal Peter Ludlow has it, human languages are myths.
But look: if Weinreich’s dictum were true, with its existential presupposition satisfied, it would follow on those grounds alone that there are dialects. And, since there are places with armies, navies and dialects, it would follow from his dictum that there are languages.
The larger issue here is that reduction, far from leading to elimination, is inconsistent with it. If lightening reduces to rapid electrostatic discharges then, because there are rapid electrostatic discharges, there is lightening. So if, implausibly, languages reduced as per the joke, that would establish the reality of languages.