The argument seems vaguely interesting but it is basically a popularization of an academic article that is linked-to but turns out to be behind a paywall, which makes the whole exercise rather useless.
You can find it on google scholar: https://scholar.google.co.uk/scholar?hl=en&as_sdt=0%2C5&q=the+lambda+and+the+kappa&btnG=&oq=the+la
Incredibly, I hadn’t heard of these terms before today, even though they’ve been around for a few years now! Amusingly enough, I worked on a Lambda architecture when I first began working on Google’s Geo data infrastructure in 2011 and over the next few years we switched everything over to Kappa without ever mentioning either of those terms!
I’m having a hard time discerning exactly what the Kappa architecture is from this article. It sounds like it’s just, “Serve your real-time and historic information with the same backend.” Is that really deserved a name? So the vast majority of all APIs are “kappa architecture”?