Microsoft isn't that powerful either. Windows is a small percentage of computing and Office simply isn't a big deal. They're also a pretty good company now.
“Microsoft. Microsoft had a market capitalization of US$ 904.86 billion for the first quarter of 2019, ranking as the largest company in the world. ...”
and that’s just the average. Today they’re a trillion dollar company. That’s 2x Facebook.
And yeah, ibm is included because it makes the mneumonic better.