I started asking my father, a concert pianist, composer, and teacher - this question when I was 4. He explained. In my head I said, “Bullshit.” I continued to press him on it periodically until I was a teenager. I still shook my head and thought, “What is wrong with these people.” Now, I can read sheet music just fine, but I still feel like … never mind. I’ve done a ton of composing without once taking any notice of what key any of it was in. And it all sounds fucking great. I prefer to do as much as possible “by ear”. I’m unbelievably stubborn.
tl;dr - Somebody really should have picked up on the autism when I was 4, and MIDI rolls don’t give a shit about keys and accidentals.
MIDI rolls don't, by themselves, make any noise or even inherently define any note frequencies at all.
The frequency of the sound produced by a given synthesizer when it receives any particular MIDI note number is up to the synthesizer. This is part of the point of the MIDI tuning system. The synthesizer and/or the tuning system may very much care about keys and accidentals.
tl;dr - Somebody really should have picked up on the autism when I was 4, and MIDI rolls don’t give a shit about keys and accidentals.