Yeah I don't think Nintendo used only for logos on SNES games, it's only added on Shenske's Vertical template.
The "Only For" logo didn't exist when the SNES was first released. From what I can tell, they introduced it around when Donkey Kong Country was released in 1994, but they never redid the packaging for exclusives produced before the "Only For" logo was introduced (unless they became Player's Choice games, which wasn't a thing until 1996), and many exclusives that were published after the logo was introduced also never got it on their box (like Chrono Trigger, which was a 1995 release)
Short version: Nintendo was inconsistent with the thing prior to the N64.