I have the same exact controller. The Akai MPKmini. My 2nd-gen 2i4 has actual MIDI ports, but I haven't had the chance to use them yet because the MPKmini does MIDI over USB. I've not done much recording of guitar. When I make music on Linux I usually use LMMS, and digital instruments. I used to only use my own music in my videos, but it's not everyone's cup of tea lol. So I started using Youtube's music mostly, but I still manage to slip some of my own into the videos.

I also have a Korg Monologue with MIDI in/out's, but I haven't had a chance to try them out. It also has MIDI over USB, and if I was controlling digital instruments I'd reach for the Akai usually since it doesn't need to plug into the wall.
I think the actual MIDI ports might be most useful when going from synthesizer to synthesizer, but it was more important in the 80's and early 90's because MIDI over USb didn't exist yet.
So the in/out on the back of my Scarlet I assume is for older synthesizers if you wanted to attach them as a controller you'd have to use the Scarlet if they didn't have a USB.