The point remains: That is still just down to how you compose the context/prompt that actually goes to the model.
Nothing stops an agent from including logic to inline the full set of skills if the context is short enough. The point of skills is to provide a mechanism for managing context to reduce the need for summarization/compaction or explicit management, and so allowing you to e.g. have a lot of them available.
(And this kind of makes the article largely moot - it's slightly neat to know it might be better to just inline the skills if you have few enough that they won't seriously fill up your context, but the main value of skills comes when you have enough of them that this isn't the case)
Conversely, nothing prevents the agent from using lossy processing with a smaller, faster model on AGENTS.md either before passing it to the main model e.g. if context is getting out of hand, or if the developer of a given agent think they have a way of making adherence better by transforming them.
These are all tooling decisions, not features of the models.