Those properties are not proprietary (the vast majority at least). There is a draft spec for most of them but agreement on the final implementation doesn't yet exist. Browser prefixes give vendors the ability to test said draft spec in the wild and correct course if necessary. They also make sure that differing implementations don't make the lives of web developers hard for decades. They are a great idea, actually.
I guess proprietary was the wrong word for what I was saying about the properties. It wasn't my aim to imply that they were proprietary features, just a lack of knowing a better term to refer to the property names.
