I wouldn't be surprised if the actual story underneath was that they got to a "works well enough" implementation and then forgot about the inefficiencies until someone looked at costs, connected the dots, and went "ok yeah we need to optimize this architecture."

I've seen some staggering cost savings realized because someone happened to notice that an inefficient implementation that wasn't a problem two years ago at the scale it was running at back then did not age well to the 10x volume it was handling two years later. The reason it hadn't fallen over was that horizontal scaling features built into the cloud products were able to keep it running with minimal attention from the SRE's.