Convenience and ease of use in managing/accessing any/all of the encrypted disk images on the Mac.
Back in the aughts ago I used to use Marko Karppinen’s Knox For Mac (review), which also had an integrated backup system. When it was sold off (to 1Password in 2010) then finally discontinued, I opted to buy Espionage… then stopped using encrypted archives for the most part in favor of putting individual files inside 1Password.
Knox:
