In a place like northwest Indiana, where the traffic is thick and the exits are only a mile or two apart, or over in Chicago where it's considerably worse, I can see why people might develop an allergy to being in the right-most lane. That's where the entry and exit ramps are, and keeping out of that lane means you're not in anyone's way.
But here in Florida, on the stretch of I-95 that I live near where there are 3 lanes to travel in and the exits are few and far between, I still see people exhibiting this allergy.
Most of the people here are from the New York area, so they probably know how to drive almost as well as I do, which makes it surprising that they would discriminate against a lane when, where they learned to drive, all lanes are needed to get anywhere.
You're supposed to be in the right lane unless you're engaged in passing someone, or if there's an emergency vehicle on the right shoulder. Most people also have the courtesy to move over if someone's trying to enter the highway. But the rest of the time, you're supposed to be in the right lane.
Why? Because doing so promotes better traffic flow. It allows the drivers anxious to get speeding tickets to get past those who drive in 2nd gear. And it's the law, if that matters.
You probably hate getting stuck behind a long line of cars, like everyone else does. If the rules of the road didn't tell us to keep right except to pass, the highways would be unbearably clogged with even half the traffic they now carry. I see it in places where this is ignored.
So do us all a favor and keep right, except to pass. And when passing, if you have to speed up a little bit to complete the operation in under 10 seconds, please do so. It's not just common courtesy, it's the law.