I mean more specifically the way the components are flush-mounted, not in the standard DIP arrangement. They don't require holes drilled in the board, and more importantly, don't penetrate the board itself, so components can be mounted on both sides if necessary without risk of overlapping holes.

I can remember building computers in the early 1990s with logic boards that looked more primitive than what was in this module from the 1960s.

Apparently surface mounting was developed specifically for the Launch Vehicle Digital Computer: https://en.wikipedia.org/wiki/Surface-mount_technology