I have noticed in the last 10 years or so that obi is often spelled as "OBI" - and now maybe that is why. Maybe it's not just this guy that thinks it is an acronym.
Edit - looking back at some of my posts of Japanese pressings, I've even used the OBI capitalization because it has gotten to be mainstream..even when I know it isn't an acronym.
Obi (sash) - Wikipedia