This limitation exercise will help you in many ways. First, you are challenging yourself with a limitation rule-set to create some kind of chord sequence that makes musical sense. This leads to all kinds of melodic harmonization options when harmonizing your melodies or other melodies.
In this exercise we use the minor "system" and don't rely on pure diatonic minor scales, but chords from "each" like master composers do.
We are also allowing forms of chromatic harmony.
Doing such things enriches even your simplest melodies with tons of harmonic choices where pure diatonic music can never go.
Limitation with a challenge is one of the best things you can practice. The more you move away from comfort, the more you learn, and the easier it becomes to do such things.
