Sam and acme do away with almost all the cursor movement commands and keystrokes of other editors, and replaces them with the mouse (to move the cursor around, just point and click, simpler and faster) and structured regular expressions (to select text segments in a document, then run commands across just those). They even use mouse chords for common operations such as cut, paste, and run a command, which are so muscle-memory to me now they don't interrupt my stream of thought.
That was my major complaint about Plan 9 in general. As far as I could tell, it really wanted me to run with a one-handed keyboard and mouse.
...that plus the fact that Bell Labs invented "Not Invented Here" Syndrome.