You might as well just write instructions in English in any old format, as long as it's comprehensible. Exactly as you'd do for human readers! Nothing has really changed about what constitutes good documentation. (Edit to add: my parochialism is showing there, it doesn't have to be English)
Is any of this standardization really needed? Who does it benefit, except the people who enjoy writing specs and establishing standards like this? If it really is a productivity win, it ought to be possible to run a comparison study and prove it. Even then, it might not be worthwhile in the longer run.
I'm very curious to know the size & state of a codebase where skills are beneficial over just having good information hierarchy for your documentation.
In other words, if you run an identical prompt, one with skill and one without, on a test task that requires discovering deeply how your codebase works, which one performs better on the following metrics, and how much better?
1. Accuracy / completion of the task
2. Wall clock time to execute the task
3. Token consumption of the task
I think the main conflict in this thread is whether skills are anything more than just structuring documentation you were lacking in your repo, regardless if it was for Claude or Steve starting from scratch.