Comment by spoiler

I think they have some good points (having a deep understanding of tools you use), but I think the path they take achieve those results is misguided.

A stupid example off the top of my head: I use VSCode and often I'll use the integrated git commit feature. But if need to bisect, rebase, merge, or edit a commit, I will just use the CLI. I don't feel like using the commit GUI makes me worse at using git.

All in all, I think the author thinks that familiarity with one tool makes people worse at another similar tool, but I don't think that's the necessarily the case. At worst, memory might fade if the other tool isn't used, but that's fine, it's clearly not used often. As an analogy: if I don't speak German every day, I don't need to be fluent in German either.