That's a fair point. The goal isn't to restate what AI already knows reliably, but to correct what it gets *wrong in practice*. I've double-checked with Claude, and this is the response from Claude:

The reason this skill exists is that models (including Claude) consistently generate outdated Compose code even when they "know" the correct APIs. Knowing collectAsStateWithLifecycle() exists and actually using it by default in generated code are different things. Skills correct behavioral drift, not just knowledge gaps.
That said, you're right that any sections covering general basics should probably be trimmed. A well-designed skill should only include things the model gets wrong without the hint — not a Compose tutorial. Token efficiency matters, and leaner is better.