I'm not entirely convinced it works out that way so far, but that's the theory.
Trying to bring down LLM costs is sort of a double-edged sword, because the dev needs to be cutting LLM costs by more than what you're paying them. If it takes them a day to bring costs down by $1 an invocation, then it takes almost 2 years to recoup the salary costs. It's worse because LLMs currently change so much I wouldn't be confident that their solution won't be broken before the 2 year period. Will we still be tool calling in 2 years, or will that be something new? Will thinking still be a thing, or will it be superceded by something else? I don't think anyone knows, even the frontier providers.