The original idea of Compressor separated by the Engine Gearbox from the Turbine is a good practical idea for maintenance at base.
Either side can be inspected and repaired without disturbing the other half.
Old idea and I understand the latest models now have a single stage centrifugal compressor which saves much wieght from the axial/centrifugal of early days.
In fix wing applications the engine Hanging from the wing supports to the ER/GB certainly help maintenance.
john