I just skimmed the first section of Learn Enough Command Line and discovered you can hold option to use the mouse to insert the cursor in the middle of a line.

I thought I knew how to use cli but now I feel like I need to go through this whole tutorial to see what other incredibly obvious things I've been missing.

I would say thats a Unix specific thing more than CLI. It will work on Linux web browsers. Unfortunately three button trackpads seem to be disappearing.

Most Linux distributions by default configure the track-pad to emulate the middle mouse by clicking the left and right button simultaneously. Not as nice as an actual third button, but useful if you are on a laptop without a peripheral mouse attached.

Last couple of laptops I have had were not able to click left and right together. Another one for aesthetics versus usability.

Thanks! As the first title in the Learn Enough sequence, Learn Enough™ Command Line to Be Dangerous was especially challenging to write, because it literally assumes no prerequisites other than general computer knowledge (not even a text editor). So glad to hear you liked it!