Generally good, but a few painful points in it.

Like his explanation of why we use command line...

it's not "because legacy" and such. However he phrased that gist.

It's because (among many reasons), it's easier to share help how to do something as a command, than a sequence of steps to go through with a gui, that may not even be a very universally used gui.

And easier to follow the help as a command (... generally can merely copy & paste).

And from having the command, you are then given more avenues to explore deeper understanding of what it's doing more up front (e.g. can run man, or tldr, or info, or whereis, or whatis, or apropos, and so on, on the command(s) and its(/their) various parts, or even try a -h or --help option after the command... reading the fun manual is good).

With Command Line Interface (cli), rather than Graphical User Interface (gui), the distance to being empowered and learning more, is far shorter, with far fewer hurdles in the way. I know it seems like the gui's the easier way, but it's only easy at the initial shallow front it offers, and it's surprisingly not faster ... "but i click, it does it, just one click, no typing" ha! how many clicks can you do, how much nuance of control is there in your click... only what the gui provides? no depth of potential to create whatever possibilities the linguistic nature of stringing commands together. And how much resources are used~ is the gui always responsive, like the command line is?

[If you were to] Try to get to a similar level of depth of capability and competence with a gui as availed in the command line, then you're going the hard long way around, having to reprogram your gui (probably in something like C, or maybe rust, and needing to know about all kinds of graphical toolkits, libraries and whatever system inner workings doodads and things). Which would indeed be great. Do that. Build and adapt guis to your liking and share them. Great contribution, great learning experience. But I'll carry on taking the easier, more expedient path, and keep using the command line. ;)

Little by little it grows, and before you know it, you're quite proficient with the command line, and no longer even want to do things through the gui, because you can do it faster and easier on the command line.

Even more so when using a shell like fish, or have run "oh-my-zsh" or "oh-my-bash" to spruce up your zsh or bash shell configurations, to have all kinds of pleasant auto-completion wonders to really expedite completing commands, way faster than typing, even faster than mere tab-completion... the wonders in store for the newcomers... they just dont know, yet. :)

Why do we tend towards cli preference over gui?

"Text is a universal interface" -- Doug McIlroy (paraphrased reduction), as part of the unix philosophy.

... Call that "because legacy" if you like, I think the "because" of it has nothing to do with legacy, and [the philosophy] is true, new, today, as it was then. "Do one thing well", too.

Not that everything need follow this philosophy, and of course many things don't, and that's the beauty of freedom. But it is very nice when there's that deep interoperability. :)