It really threw me off when they referenced "International Business Machines Corp." instead of IBM...I can't name another instance where someone decided to use the full name of IBM
Hah, same. It's like seeing someone spell out Advanced Micro Devices (AMD) or Minnesota Mining and Manufacturing Company (3M). Just kinda weird.
Most professional news organizations have style guides that govern how to reference companies, states, titles, measurements, etc. For some really common acronyms it seems like overkill (IBM, FBI, etc.) but the copy desk will still enforce it.