UI discoverability has massively declined with the advent of touch UIs though. You can't hover a UI item to see what it does, and there's a lot of non-intuitive "magic swipes" and hidden UI elements in smartphone UIs which you just have to know about.

Your argument applies to all kitchen sinks, regardless of whether they are considered one application like VSCode or an operating system withs collection of applications like Unix. Both still have all the capabilities for text editing, syntax highlighting, version control and executing scripts. You can spread complexity around in different ways but you can’t eliminate it.

Personally I find GUI discoverability to be like the hunt-and-peck model of typing, vs touch typing being CLI, and I don’t think it’s a coincidence that touch typing and CLI go hand in hand: you never leave home row. You think about what you want to do and type the command, instead of looking through panels of icons or more exotically arranged buttons (which in the newest web apps, constantly jump around as the page lazily loads, new elements appear forcing layout changes, fonts load causing text reflow… I frequently tap the wrong menu item because what I really wanted got pushed down by a new appearing element as my finger approached the screen.)

I agree with you about discoverability, but in practice I find that tasks aren't completely new every time, there usually are common principles. With usage, you kinda get to know what is and isn't possible, even if you don't recall the precise details of each and every command. So you can look them up, knowing more or less what you're looking for.

On Linux, `--help` usually... helps. Or there's the man. On Windows, the MS docs are usually usable to find things.

Of course, it may not work 100% of the time, but I find it's a question of philosophy. I'm not a Windows user, so I generally approach it with a mentality of "it would be nice to be able to do this, let me check real quick if there's a way". I usually manage to not have to click around for two hours when I have to do something repetitive.

Uh no.

Take clicking around a Microsoft ISS configuration on Windows 2000 vs an Apache httpd config file and it’s online doc.

I briefly tried both, and didn’t look back

I think I saw a command line tool that would show the documentation for all flags when you pressed tab... I don't remember it's name, though.