In fairness, I have not read the 37 page paper yet. Maybe the paper makes a more compelling case than the summary article.
A driver, besides the cost of the car and fuel, faces a time cost. An extra lane will reduce the time-cost, assuming no new vehicles enter the road. But if time costs fall, it's in effect 'cheaper' to drive. So previous car trips that were not happening, because the time-cost was too high, are now occurring. The amount of extra car-trips is such that we are back to the same time-cost as before the road expansion. That's why VKT ends up growing one for one with road expansion.
To me this says that lane expansion is not the driver of KVT (at at least not the primary one).
The broad question is what would reduce congestion - currently, on the margin, adding a lane will not reduce it. I imagine that hypothetically adding many lanes may reduce congestion, although there may be city driven bottlenecks that don't make this feasible at all.