@bartavi A bit of both plus a decision by an early terminal manufacturer. catonmat.net/why-vim-uses-hjkl

ASCII had already defined the codes and 8 (aka ^H or backspace) and 10 (aka ^J or linefeed) already had a kind of intrinsic left- and down-ness to them. 11 and 12 (^K and ^L, or vertical tab and formfeed) kind of implied motion, but had more meaning when terminals printed to paper rather than a screen.

The folks at LS decided since your fingers were already there, why not complete the arrow set.