What are locknuts?
Locknuts are special components that create a solid metal thread in the wooden board, which allows the board and base to be assembled and disassembled an unlimited number of times without damaging the board.
Classic screws only hold fest the first time. Once you loosen them, they'll never hold as well and you'll have to figure out what to do with a table that has a loose top. To keep the wood from chewing out every time you tighten it to the base, just put cotter nuts in the top and your worries are over.
We use nuts for all boards, except for thin shelves on coffee tables, where they cannot be screwed in dimensionally.