Currently the only thing holding me back is that my particular phone (S9+) has fairly limited resolution support. IIRC the Note models are supposed to do much better as they have a discrete GPU for Dex output.

But basically all my day-to-day development tasks can be done on Dex and a SSH/terminal app.

AFAICT, there are two main reasons it hasn't caught on:

1. It doesn't follow the normal technology adoption curve. Most tech is adopted first by technically savvy individuals who know how to deal with the "quirks" of living on the bleeding edge. And then evangelize it to the normies.

But a docked phone is for the normals, only techies need the power of a standalone computer.

2: A monitor + keyboard + dock can be more expensive and less convenient than a chromebook.

But it's an obvious idea and eventually it will happen. Once Google and/or Apple takes it seriously and integrate it into the base operating system, it'll slowly spread.