Hi Chas
Organs are used in plenty of top tier establishments, and arranger keyboards are just single manual organs, (Hence you can add a second keyboard and pedals) so that’s one theory that doesn’t hold water.
As to Midi files etc, then if the user has created these themselves, and they play everything else that is possible, then you are still hearing just there own performance, but much more enhanced and realistic.
Theatre organs had pianos, drums, whistles and all sorts added to them which were not played by the organist, but just triggered from the keyboards and or tabs, which in your eyes I presume means even these players/instruments are not professional. (And should not be listened too)
Always look at the bigger picture.

Bill