Many LP's tend to have raised edges and slightly raised label areas, so grooves sliding against each other wasn't necessarily an issue. The Garrard Lab 80 and aforementioned Duals had a gentle 'umbrella style' stacking spindle which claimed to lower records to the platter on a cushion of air, rather than push them off a step in the spindle and 'slapping' them onto the record rotating beneath.
I agree about modern fancy 'fine-line' and similar diamonds finding parts of the groove undamaged by ancient conical styli. Old LP's can be cleaned to good effect too.
P.S. Not sure if these old 'pop' hot single cuts (often the masters were hot as well) transfer well to 'digital' (as in singles compilations on CD), as the mixing techniques used are shown in all their glory without the crystal or ceramic cartridge to balance it out
