Because we are not all geniuses.
No author’s byline, no authority.
In standard Italian, Arneis is ahr NAY ees. The dialect pronunciation could be ahr NASE, but I’m skeptical.
Vinho Verde is VIN yo VER jay.
I’m not sure there is an authoritative guide to pronouncing grape and wine names. None of my wine references include that.
Portuguese can make ya nuts 