Still, this is an argument for upgrading all "pipes", not one for attempting to control demand on the supply/capacity side.
But even absent that, you want surface, collector, and feeder streets to be the natural "rate-limiting" parts of the network (in that order).
It's why it's especially egregious to wave-in people from a driveway or parking lot into traffic on an already congested street. It breaks the natural rate limiting.
The right-of-way rules are surprisingly well-thought out, from a systems perspective.
Improving capacity and traffic flow doesn't always have to mean widen.
But the point is that you increase capacities where you can, and that it's better to start large with freeways, etc and work your way down, even if freeway capacity then exceeds feeder capacity (which then exceeds collector capacity, exceeds surface capacity).
But even absent that, you want surface, collector, and feeder streets to be the natural "rate-limiting" parts of the network (in that order).
It's why it's especially egregious to wave-in people from a driveway or parking lot into traffic on an already congested street. It breaks the natural rate limiting.
The right-of-way rules are surprisingly well-thought out, from a systems perspective.