The main point of this article wasn't that these things are never needed or don't solve a real problem, but rather that a lot of people use them "because hype"

The main point of this article wasn't that these things are never needed or don't solve a real problem, but rather that a lot of people use them "because hype" without a good understanding of their problems, the strengths and weaknesses of these tools, etc. UNPHAT is a good approach. Any webshop essentially has Amazon's "a failed add to cart will lose us money"-problem and there are a lot of webshops out there, so it's even a common problem! Cassandra may be a good choice even for a smaller webshop (I'm not familiar with it myself, and may be a poor trade-off with respect of ROI, but that's another thing), but it's definitely not a good fit for a lot of other things like batch jobs. At my current $dayjob we run a low-volume high-profit B2B business; we have a few hundred customers, and it'll never be more than a few thousand – several ten thousand at the most if we end up wildly successful. It's a whole forest of microservices and will scale to the moon, but it's also pretty complex and difficult to work with. All that for a fairly small customer base using a fairly basic web UI they rarely log in to. We do actually have high-availability requirements in the core business, but that's separate from the management UI. It's a good example of not having understood the actual problems and just using something "because I read about it on Hacker News".