We see this in the short term, too. LA had their Carmageddon that -- lo -- never came to pass, and Chicago just shut down the Kennedy through the Loop for the past two weekends...and it was a non-issue.
Best analogy I've ever read (and I'm paraphrasing) was that two people had to race to get as many pinballs through a tube to a barrel at the other end as possible. They both started with the same number of balls. Person one could dump them into a funnel that had a tube going to the barrel. They could do it any way they chose (one at a time, with a bucket, etc). Person two had the same number, but they were all put into smaller PVC pipes of like 50 in a row, preloaded. Which probably gets all the balls in the barrel faster every time?
It's not a matter of bandwidth, it's a matter of efficiency. If anything, more room creates more ability for drivers to try and disorganize, and that's what creates traffic problems.