While, as others have pointed out, there is an in-game mechanic to deal with this, players need to have their hands held harder because there are too many 0-1 chests when you join a group thinking it's a 2 chest. A large part of this, sadly, is party leaders deceiving players.

I wouldn't object to hard instance lockouts (vs loot lockouts) to deal with this once and for all. Yes, it doesn't let you help others out, but there is too much volatility, frustration, and griefing with 0-1 chests as-is.