Thanks for checking it out! That is definitely a valid point, it would lead learners to develop their skills faster. Another example would be only allowing hjkl movement and disabling arrow keys.
Disabling mouse selection in the editor might be too restrictive, because I want learners to find what works for them. As it is, I can only expect the learner to practice with good faith along with the lessons.
However I could also add an option to turn on a more restrictive practicing environment (only limit to certain commands, no mouse usage, etc.)