The sad thing is that Windows has a great keyboard UI and it's superbly accessible for people with visual and motor disabilities.
Who have reduced earning opportunities because they are disabled, so FOSS should be great for them, but it isn't, because the nerds don't know CUA and don't know the keyboard UI. They spend their time mastering a couple of ancient apps like Vi and Emacs and ignore the fiery furnace of UI R&D that followed for the next 20Y after those early efforts.
Learn Windows' keyboard UI and you can drive the whole OS and all its apps with the speed of a genius Vim user with 20 years' practice. It makes Emacs look like a wet paper pad and a burned stick compared to a Moleskine notebook and a top quality fountain pen.
Xfce comes close and implements maybe 75% of the UI but once you are in an app all bets are off.
Do you have a reference for this? I've often needed to control Windows using only a keyboard and failed to do so. I'm aware of most shortcuts in this list[1] but these are for a few very specific things. (As an aside, I also remember controlling the mouse with the numpad using the Mouse Keys accessibility setting but this is worse than both keyboard shortcuts and the mouse.)
[1]: https://en.wikipedia.org/wiki/Table_of_keyboard_shortcuts
Look for underlined single letters in menus. With apps that use the "classic" style menus instead of ribbons or plain Electron crap, the single letters are the key.
For example, I would like to set options that are a few menus/button clicks deep in the Windows control panel (either the "classic" or new variant) using keyboard shortcuts/navigation. Or navigate the Windows registry editor. I'm not aware of a way to do this.
No, it's not in all OSes. I wish it were.
No, it's not in all native apps. KDE reinvents its own set of keystrokes, for instance, and half the KDE apps have no menu bars any more... And there's no global way to force them either.
Yes, the control panel and RegEdit are totally keyboard controllable.
You can literally just unplug the mouse from a Windows desktop and it remains totally 100% operable.
Some apps may not, because the developers didn't do their jobs right, but the OS is.
How else could blind people use PCs?
https://en.wikipedia.org/wiki/IBM_Common_User_Access
There are dozens of them out there.
Random example:
https://www.system-overload.org/windows-shortcuts.html
General guide...
Activate menu bar with Alt. Alt + the underlined letter opens that menu or submenu.
Alt+Space opens the control menu for that window. In MDI apps, alt+hyphen opens the document's window control menu.
Then...
Alt+space, x = maXimise Alt+space, n = miNimise Alt+space, s = reSize followed by cursor key to select which edge, then cursors to change.
Hotkeys are Ctrl+letter and do that action now.
Ctrl+... p = print s = save o = open f = find c = copy x = cut (looks like scissors) v = paste (looks like an arrow: paste _V_ HERE )
Shift modifies or reverses many commands, and selects while moving.
In dialogs and forms, Tab moves forwards; Shift+Tab backwards
Ctrl+PgDown = next tab Ctrl+PgUp = previous tab Ctrl+Enter = save and close form
Ctrl+left/right = move by word instead of character Shift+home/end = select to start/end of line
Esc = cancel
Ctrl+Esc = open start menu
Then tab, and you're tabbing through the taskbar, which is a sort of dialog box.
Ctrl+Shift+Esc = open task manager
Maybe this should be on a wiki somewhere so it can be documented collaboratively...
I'm sure you can give me some hints, because Microsoft, can't.
Windows also has a great help system, online. /s
Back in the days when application developers stuck to the Windows-provided widgets instead of doing their own UI, it was wonderful. Symbols were consistent across applications, as were color schemes (IIRC, if you wrote your CSS correctly, Internet Explorer would pass these on to websites!) and behavior.
I miss these days.
Or the documentation is very complete, but only useful if you read and comprehend it in its entirety. Open source devs need to understand that not everyone using their software wants to become an expert in it. They just want to get a task done and the software is facilitating completing that task. That is something totally normal and those users should not be thought of as less important than the power users.
The problem is, most users are utterly braindead, they barely manage to type at speed instead of pecking at single keys. The astonishment I've gotten in some places for literally nothing more than Ctrl+C/Ctrl+V is more than enough proof.
That's also IMHO a large portion of why Linux never really took off on desktop. UX/UI people are rare enough to begin with, most of them don't work on FOSS in their free time, and so development is primarily done by nerds for nerds. That's great if you already know something about the application - but usually the learning curve is so steep that most users frustratedly give up. And documentation is either not existing, incomplete or horribly outdated, and StackOverflow etc. are even worse.
The exception is Blender. They got some serious money IIRC, cleaned up their act, and now there's a headline of some movie or game using Blender every few weeks.