That is a little like calling the new M70 an FN, not a Winchester.
Yes, the Vanguard line is manufactured by Howa in Japan but, if you go to the Weatherby website, and/or their forum ('Weatherby Nation'), you will see that Weatherby considers the Vanguards to be REAL Weatherby's. And like it or not, in today's global economy, where things are made and by whom is unimportant.
And yes, the Mark V line of Weatherby's are still considered to be their "flagship" but fancy stocks and engraving do not really enhance quality; indeed, most Weatherby owners and the Weatherby company concede that the Vanguard line is at least as well made and usually more accurate. Why would this be? Well, perhaps it is because the Howa is actually a direct copy of the Sako Finnbear rifle, with receiver and barrels made using machines imported under license from Sako:
http://www.weatherbynation.com/spikecamp/conversation/24/vanguard-history-part-i/0/?wap2
So, if you want to say that "the Vanguard is not a Weatherby", then it would be just as correct to say that the Vanguard is a Sako with "the Weatherby name stamped on it". The quality of construction and the accuracy of Sako Finnbears is legendary (
I can personally attest to that as I own 2 of them), and Howa and Weatherby have benefited from this evolution. So much so that, if you visit the Sniper's Hide forum, you will see that (as well as Sakos) the Howa/Vanguard actions and barrels are highly prized and used by many expert gunsmiths to make extremely accurate tactical rifles.