You’re indeed correct. All the borderless cards (I’ve added examples from my collection below) are drawn by Kazuki Takahashi himself. But those are kinda the exception. There are a lot of different Yu-Gi-Oh illustrators, but except for Kazuki, none are mentioned/credited on the cards themselves.
(These were all copied from my Yu-Gi-Oh Rarities Guide/Collection, which is long due for an update… 
)
Greetz,
Quuador