You can argue that the command line interface was a barrier to computing, but that's like arguing that the stick shift was a barrier to car ownership. First, plenty of people bought both products anyway, and plenty of those and other people still rely on the earlier interface because it can do things that the newer one can't. So... the most you can say is it was a barrier to people who couldn't figure out that earlier interface, be it the command line or stick shift. But that's not to say the newer interface is better, or even necessarily simpler. It's just different in a way that more people can seem to grasp.
In some ways the CLI was easier for low-tech saavy people. These days everyone is used to tech, phones, and GUI interfaces in general. But in the 90s, I would
frequently run into people who did not understand tech at all, or they were afraid of it, afraid of screwing something up. They needed a computer to do their job
but would demand step-by-step instructions to run the tasks they needed.
In DOS/Cli, this was easy, you put all the commands into a batch file, and told them to type the name of the batch file.
But with a GUI, trying to give such step-by-step instructions was a nightmare. It was like you have double-click this icon, but the icon may or may not be on screen it may be
in a window that's minimized, or the app may already be running and you have to maximize it. If they clicked out of the app, you'd have
to tell them how to get back into it. And they would panic if anything didn't go like they expected.
Even the concept of double-clicking was hard to grasp for some of these people, they would generally click too slow at first.
Like I said, today people are pretty tech-saavy and I never run into this anymore. Back then it was not uncommon.