The point is to use low-end machines for a number of logic that 99% will do nothing. As example: webhooks.
In this scenario there is no need for high performance/low latency but there is a high demand of low resource usage.
However there's a way to scale it horizontally using shared storage. But it should out of scope.
Btw I am author of it and I will be happy to answer on any questions. Thanks for your interest!