The main benefit here is not in how accurate the metaphor is today, but how consistently it is used. Save looked roughly the same in the 90s as it does today, a

The main benefit here is not in how accurate the metaphor is today, but how consistently it is used. Save looked roughly the same in the 90s as it does today, across operating systems, across applications, and it's instantly recognizable. Perhaps what's a good comparison is traffic signs: no entry has very little metaphorical meaning but it's universally known and understood.