If you clicked the article, you would see that it is in the first few paragraphs in bold: marketing and sales. Pretty much what most growth companies have to spend on in the earlier stages.
I'm a happy customer of Wavefront. I completely believe that Datadog can handle hundreds of thousands per minute -- especially if most of them are pre-canned, non-custom metrics grabbed by their agent. Hundreds of thousands of metrics/minute is a few thousand a second only. Wavefront does millions of custom metrics per second, which can be sent with different dimensions and tags. That's much harder.
Datadog may be okay if you're doing really simple stuff and not sending much data. Once you get to scale, you will need a system like Wavefront. Wavefront can take millions of data points per second, query on them super fast, and they don't go down. Every other monitoring system downsamples, or throws away your data after a certain amount of time.