What tomlee59 said. The adapter is just there to get the signals outside the box. It doesn't do any conversion at all. It was left up to the monitor or a second adapter to cope with what it was given.

Remember, this is what the Mac market was like in the day. It wasn't that long since there had been several major forces in the personal computer space, each with their own lines of software and accessories, and their own standards. One by one they fell to the Wintel juggernaut. Apple only started to admit defeat, if you will, or get with the program, if you'd rather, around the mid to late '90s when they moved from Nubus to PCI architecture. Even then, it was several years before the proprietary Apple monitor plug fell by the wayside.

Don't mistake the dominant norm for a standard. A standard is agreed upon by several independant parties and/or an engineering committee, not enforced by market power and illegal bullying.