The point of the article as I understand it, is that Google itself even without special commands is a "command-line" tool in a sense that you more often enter text rather than click.
This kind of "cmdline" tools win in some specific areas because they work perfectly with thin clients and via thin communication channels. All you need is to send a couple of words to the server using some relatively simple standard local application - be it a browser or your console client.
I'd postulate that it was the adoption of the GUI that let the PC spread into the mainstream. Most people just don't have the patience to look up commands. Periodically, there are nostalgic pronouncements that the command-line will reign supreme again, but mostly this seems to be because the tech pundit population largely overlaps with the comfortable-with-computer-before-they-became-mainstream population.