I think you are focusing a bit too much on legacy MIDI ports. Nowadays, the USB port provides all the MIDI connectivity you need, and push comes to shove and you have a dinosaur in your rig with no USB, there are inexpensive USB to MIDI converters.
Life has become a whole lot easier with USB!
Yes when it’s Midi to USB. Not usb to midi.
I’m not sure you are aware that it doest work in reverse. It always require external box with own power supply or computer in between.
Show me how you connect say P125 to sx900 with one cable without converter box ( which always require power supply ). There is none because keyboards uses USB B connector.
There is a reason that Pros require midi outs in Live situations. One simple cable between two Midi equipped gear. No dongles/ no extra boxes/ no adapters/ no computers in between.