That would achieve 1 of the 3 wins.

If you use a smaller model for the sub agent you get all three

Of course you can combine both approaches for even greater gains. But Claude Code and like five alternatives gaining an efficient tool-calling paradigm where console output is interpreted by Haiku instead of Opus seems like a much quicker win than adding an LLM env flag to every cli tool under the sun

Probably the main one, people mostly complain about context window management rather than token usage