If someone needs to rest, they can, but they have to rest for 10 days. It's like the DL list in baseball and football, which makes more sense because teams need to fill out their rosters, but it could work for the NBA.

Of course thinking about it, teams counter this by just sitting players they want to rest 4-minutes into a game. NBA teams don't really go to their #14 guy on the bench ever, even when resting their stars.