In the Arch Linux console,
M-b (alt-b) moves back one word with
us layout, but after
loadkeys carpalx-full, it
doesn't (b is now at y). Why not? I have looked at the keymap
files, but couldn't find any explanation.
Most likely because the code for the console is written to read directly from the keyboard-device (a file in
/dev/input/by-path) instead of reading from
/dev/stdin. When you read directly from the device keymaps are ignored.
If this is indeed the reason then you should notice that all other keys also act as if the keymap wasn't changed. (I don't have Arch so I can't test it.)