As a relatively new ham operator, I understand that it is customary to use lower-sideband below 10 MHz and upper-side band above 10Mhz when operating single-sideband HF. I'm curious how we got to such a standard instead of just picking one or the other for all bands.
To further complicate it for new hams, it seems that RTTY operators use lower-sideband everywhere and PSK operators use upper-sideband everywhere. (Reference)
Is there any technical reason not to use upper-sideband everywhere? Or is this purely tradition to be passed on for the sake of tradition? Does anyone know some verifiable history for how this de-facto standard came to be?