why were does it imply that the order are the only one who do this???
Just accept the fact that the Volkihar were carbon copies of the Order. Volkihar didn't even make it into the list of "enlightened" vampires in the manifesto

. If anything, the Whet Fang are suppose to be the smarter ones, such as the Glenmoril Wyrd. Bethesda just wanted to make gameplay more fun.
Fans: "Wuaaaa! I want Volkihar! Ice breaking powers and paralyzing effects!"
Betheda: "What do we do? I know. We can copy the effects of vampires from Oblivion and add them to these vampires we label as "Volkihar" and then give them wings and rip off from Underworld."
Don't get me wrong, I love the Vampire Lord appearance, but to make them Volkihars? Pfft.