This is in practice not true at all. Vertical scaling is typically a sublinear cost increase (up to a point, but that point is a ridiculous beast of a machine), since you're (typically) upgrading just the CPU and/or just the RAM or just the storage; not all of them at once.
There are instances where you can get nearly 10x the machine for 2x the cost.
(and fwiw, wikipedia agrees with this definition: https://en.wikipedia.org/wiki/Scalability#Horizontal_(scale_... )
> Vertical scaling — a bigger, exponentially more expensive server
> Horizontal scaling — distribute the load over more servers
The fact that AMD chooses to package the "nodes" together on one die vs multiple doesn't change that.
> typically involving the addition of CPUs, memory or storage to a single computer.
Distinction between horizontal and vertical scaling becomes nonsense if we accept your definitions, because literally nobody does that sort of vertical scaling.
* Replace the CPU with a faster one, but with the same number of cores. Or simply run the same one at a higher clock rate.
* Add memory, or use faster memory.
* Add storage, or use faster storage.
These are all forms of vertical scaling because they reduce the time it takes to process a single transaction, either by reducing waits or by increasing computation speed.
> It's also contradicted by both the article we're discussing and the wikipedia article
The article agrees with this definition. Transaction latency decreases iff vertical scale increases. Transaction throughput increases with either form of scaling. Without this interpretation, the analogy to conveyor belts makes no sense.