If all you need is to be intelligible to the (same, small group of) people you see every day, then a local, short-lived argot will suffice.
If you're talking to people in the next village, town, state, country, continent, and/or planet over, regularly, you're going to need a more stable form of spoken comms, and coordinated evolution is more challenging.
Much as small island populations tend to evolve and diverge more rapidly than large continental ones.
