So, can we think about distortion as a kind of machine harmonization?

And if yes, can we consider another kind of machine harmonization which would be to add notes to create wanted harmonies, based on an incoming note (modulating velocity, and maybe timing, so as not to overpower the original note)?

And if yes, this could be called "MIDI distortion"... Are there MIDI plugins that do this?

I recently started making (very simple) plugins in the Reaper DAW; it would be possible to do such MIDI harmonization in JSFX. I'm wondering if it's been done already.