Because there are very few situations where a stroad is actually appropriate. If your goal is to move people, a limited access high speed road is the right way

Because there are very few situations where a stroad is actually appropriate. 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.