In a nutshell: Rails isn't shinny anymore. By migrating from (now) old Rails to new shiny Go, people can write these kinds of articles and pretend to be cutting edge and forward thinking.
its a bit more complicated than not being shiny anymore. For a lot of veterans, what's touted as best practices in the Rails community lead to maintenance headaches and performance issues in large scale long-lived applications. Rails apps tend to have a high degree of coupling internally and to gems that Just Work™ (except for when they Just Don't™).
Also, as the industry has shifted away from monolithic web frameworks to tightly controlled 'microservices' then the relevance of something as heavy as RoR wanes.
Yeah, the whole industry cycles between ideals; each generation rediscovering the benefits and drawbacks of each. Hence the renaissance of event driven applications.