The Apple ][ series had a similar "feature". At the standard BASIC prompt, pushing right-arrow would advance the cursor over the character displayed to the rig

The Apple ][ series had a similar "feature". At the standard BASIC prompt, pushing right-arrow would advance the cursor over the character displayed to the right (whether or not it was part of the current "line" you had typed so far), and – crucially – add it to the internal command buffer. On its own, this is a useless quirk, but you could also push Escape (I think) to temporarily disable this behavior, permitting the arrow keys to freely reposition the cursor on screen until you hit Escape again. So if you wanted to "edit" a line, you would list it out to the console, press Escape, move the cursor up to the start of the line, press Escape again, move the cursor right over the stuff you wanted, press Escape again, move the cursor somewhere else, press Escape again, type whatever it was you wanted to insert, press Escape again, move the cursor back to where you left off copying, press Escape again, move the cursor right over the remainder of the line, and press Return. And then Beagle Bros came out with GPLE and ushered us into the modern era of proper line editing. What a comparative luxury that was.