This feels like saying that we should only have supercomputers and low-power embedded devices, and nothing in between such as regular desktop computers.
Having two classes of devices would be an improvement of the current situation.
If your goal is to move people, a limited access high speed road is the right way to do it.
If your goal is to support commerce, a low speed, mixed traffic street that can support a lot of homes an businesses in a small area is the right way to do it.
The high speed and land use of stroads makes them inefficient and dangerous for commerce, and the fact that there's so much on-and-off traffic makes them slow and dangerous for transit. They are the worst of both worlds.
Strong Towns appears to be arguing that the trade-off between movement (roads) and value (streets) is highly non-linear, and that the middle-ground's combined performance is so much worse than either a street or road that it's not worth building. See the comment below about counter-tops vs. stoves for an example of an extreme binary case.
Correct. Because as a sibling comment notes, they are a "compromise" that serves neither purpose very well. See the Not Just Bikes video referenced elsewhere in this discussion for a fuller treatment.
The point they're trying to make isn't "you should only have tiny side streets and massive highways, with nothing in between". It's "don't build roads that require you go from a driveway or parking lot straight into high speed six-lane traffic". Drivers need reserved space for speeding up and slowing down, something that stroads do not provide.
* to be able to walk from business to business in minutes or seconds * to feel safe walking across the street * to be able to have conversations with other people outside without having to yell over traffic.
The stroad is also really bad at providing these needs because pedestrians are not considered at all in US roadway design.
(In math, that would be like saying that a homomorphism exists because you feel like it should)
Roads can move a lot of people and material long-distances, quickly. CLIs are powerful, but I've never seen an e-commerce application with a command-line interface. It'd be the wrong tool for the job.
Similarly, you shouldn't build multi-lane roads with wide lanes (which is all a great fit for highways) in places where you expect a lot of people to be, especially if they're shopping.