I don't like Boise traffic, and when I first moved to Idaho I was surprised that it was worse than some places in CA, but it's certainly not in the Los Angeles tier. I do time my trips there for non-rush hour times whenever I can.
Certainly, as the article says, part of the problem is over the top recent growth way, way beyond infrastructure capabilities. They've been working on I-84 expansion for some time. I think it's supposed to be done by next year, but as far as those extra lanes go, nature abhors a vacuum, so I'm sure they'll be full pretty quick.