Well, I know B/X better than 5e, but what you say is my impression.
B/X has rules for timekeeping, for a random encounter cycle and a rest cycle based around that, a relationship between movement rates and typical dungeon distances that means that exploration activates the time-based cycles. And rules for opening doors, listening at doors, finding and triggering traps, etc, all of which underlie the exploration focus.
Light (and hence vision) is also more tightly rationed, as torches or lantern oil have to be purchased, and the Light spell is not a freebie.
I would say that these are the basic mechanical components of the process of play that underpin B/X exploration.