I think the title is a little, I don't know, trollish? Unnecessarily controversial?, but I think the insight is true: it's very good to have some knowledge about things outside of "your area," instead of being too hyperfocused.
However, I think that's a broader thing than just "technical" knowledge: you should know a little about what your customers do, what your manager does, what the role is of systems peripheral to yours is, etc.
On first pass, it seems vague enough to border on click bait. Shallow compared to what? No knowledge? Adept knowledge? Expert knowledge? Is the argument we should intentionally stop at "shallow"? Why isn't this clear?
But, with the added context that it's from a personal blog, we should give the benefit of the doubt that the author is just not good at writing headlines and give the article a shot on its own merits...