The thing is, it doesn't. It requires the device to be able to do a Digital to Analog conversion. In modern graphics chipsets, that capability is only needed for legacy compatibility with CRTs and old projectors. If you speak VGA to a projector or any flat panel monitor, you're really just feeding an Analog to Digital converter. It's nuts.
VGA has lower quality at high resolutions than something like DVI, DisplayPort, or HDMI. Then again, if the place still has a VGA connector, it's unlikely the projector is high-resolution.