The Windows MIDI/USB stack adds considerable amount of jitter to the MIDI clock, compared to the much superior ones in MacOS. I will fully admit that "unusable" is a personal opinion based on my experience. Of course performers also use Windows, but I heavily doubt you are able to see which device in their rack acts as a master clock, and how they sync their devices, apart from the fact that most performers nowadays don't use MIDI at all.
Midi is used heavily for guitar patch and lighting automation as well as triggering backing tracks in a DAW running on stage. The use of MIDI (over USB) has only increased on stages.
This is getting ridiculous, we are talking about making music, so triggering notes from different devices in sync. You know, what MIDI was originally designed for, not triggering some lights, guitar patches or a background track. You are exactly proving my point: MIDI nowadays is pretty much reduced to SysEx for doing simple automations. None of that is seriously affected by jitter in the ms range. You sound like you have no idea how electronic music was done before VSTs were a thing.
