I'm not the brightest bulb on the string, and I sort of get the concept of 'induced demand', but there must be other factors at play. Population growth will obviously increase demand on everything from roads to transit to sidewalks, but four-laning Hwy 11 to North Bay, 69/400 to Sudbury or Hwy 416 haven't turned them into bumper-to-bumper.
Another dynamic involving heavy trucks in stop-and-go traffic is, in addition to simply consuming more real estate, they accelerate and decelerate (particularly accelerate) differently than smaller vehicles. Moving CMVs to Hwy 407, in the near term anyway, I think would have a significant impact on Hwy 401 movements.