I recently wrote that you don't need to attain a high-level of coding skill for learning to code to be useful. A technical writer can see substantial ROI from just learning enough to be dangerous.
Which raises (not begs!) the question: How much is enough? What topics should tech writers know? And how well should we know them?
To start answering that question, I'd like to expand what we mean by "learn to code" or "knowing how to code" to "developer skills" in general. Too much focus on coding overlooks the other highly useful things that developers know and do that tech writers can benefit from.