I don't think there is any attempt at lock in here, it's simply that skills are superior to MCP.

See this previous discussion on "Show HN: Playwright Skill for Claude Code – Less context than playwright-MCP (github.com/lackeyjb)": https://news.ycombinator.com/item?id=45642911

MCP deficiencies are well known:

https://www.anthropic.com/engineering/code-execution-with-mc...

https://blog.cloudflare.com/code-mode/