No one ever said a VPS with a shell script is terrible. You think of scale the wrong way. Scaling is not only about increasing from 10 requests / second to 1000 requests / second. Scaling is about organizational scale too, i.e. how do you ensure going from 2 to 20 developers increases productivity by at least 20x and not 1.5x?

Tools like Docker, Kubernetes and whatever absolutely help in that regard.