I completely agree that this is not relevant for anyone running such workloads, the article is not aimed at them at all.

Within the constraints of my setup, postgres came out slower but still fast enough. I don't think I can quantify what fast enough is though. Is it 1000 req/s? Is it 200? It all depends on what you're doing with it. For many of my hobby projects which see tens of requests per second it definitely is fast enough.

You could argue that caching is indeed redundant in such cases, but some of those have quite a lot of data that takes a while to query.