Well, TBH, I'm not sure what they're saying, but this is my thought experiment:
Imagine the doctor gave your daughter/son a pill and told you the "most important" possible adverse effect is a skin rash.
Then your child ends up in the ER with a blocked artery that needs "revascularization" (i.e., surgery) because that's also a possible adverse effect of the pill.
You ask (read: "confront") your doctor about this, and s/he says, "Well, I said rash was 'most important' because that's the most common. I didn't mention the part where it might give you a stroke or heart attack because more people got a rash."
I don't know about you, but I might need a tooth removed from my knuckle.
The idea that the rash and a stomach cramp are the "most important" adverse effect associated with Iclusig is, IMO, just not correct. "Most prevalent"? Sure. But say that.
Anyway, it's just a paper. Doctors shouldn't prescribe without reading the label. But it's mentally sloppy, IMO. That's all.