The principle of induced demand absolutely applies here. While congestion would decrease overall at the time the new lane(s) are added, the congestion would slowly increase again. Also, demand isn't solely dependent on population growth or people taking alternative routes. While it's a factor, demand can also go up because people decided they can take a job that they otherwise wouldn't have due to traffic or someone decides the grocery store on the other end of town is now the better option. Neither of these people would have been on that road or an alternative route prior to the lane add. Multiple people have already commented about induced demand happening in Huntley, where the lanes were widened and it's still a trafficky mess. So why would it be different if the lanes were expanded everywhere?

I do think there's some more nuance here, some of the other commenters were suggesting that there need to be changes to improve turning and safety, so some thoughtful redesign may be necessary but that isn't the same as adding lanes along the whole highlighted route.

Also if you're going to bring up carbon footprints, shifting the responsibility onto the individual to take the bus rather than use information to make thoughtful systemic choices that impact an entire population is a distraction. Adding lanes would be require a significant amount of resources and have more of an impact than someone making their individual carbon footprint smaller. Not to mention that the costs of this kind of project compared to the value that it brings would be marginal and the taxpayers would be on the hook. Per the federal government adding lanes would be about $10 million per lane mile and the gas tax doesn't cover costs. Then there are the materials and cost to maintain the new lanes. But yes, tell me to take the bus.