[kaiby]

The issue with that though is that if someone could read/write code, they would probably choose to be a SWE instead of a tech writer.

I'm not sure why this is, but I suspect that it's an combination of higher pay and an interest in writing code over writing documentation.

In my experience I would say that a good SWE will attempt to write good documentation, as having to answer questions in the future about how stuff works over and over takes more time than just documenting things properly the first time.