I don't understand at all how some growth is a required precondition for continued existence. There is no rule saying that companies must grow or else they automatically vanish from existence.
I think it's pretty well explained above, costs grow, unexpected things can happen, things you use wear out, and the market you're in will change over time. If you don't grow at least a little inflation will drown you in rising costs. If you don't grow a little you'll be less resilient to costly shocks. If you don't grow and preferences change, you'll be stuck producing something no one wants anymore. Any of these things can kill a firm. Growth allows you to reinvest and adapt.
