I think the major point of this article is for engineers to focus on innovation for business, rather than optimizing infra to support app new trial. Then a scalable and agile stack is critical for choice.
If you're always focused on just building new shit instead of maintaining the stuff you build, then you will always be building nothing but shit.
Try doing nothing but building new toilets without ever understanding how they work in the real world, and without learning any lessons about how they work at scale.
There has got to be a good balance. Without that, you are lost, as is everyone else that is involved in that project.
A relational database scalable for the billing data volume, should be a best answer, in term of realtime process and analysis,say complex query.
Suggest an article of a big logistics company case here, not only billing, but also order, messaging, transshipment:
https://en.pingcap.com/blog/how-to-reduce-cost-per-order-wit...