Actually, that brings up a good reason they can't fix it. Fable falls back to Opus when the topic is too "unsafe". That behavior requires traces than can move between models!
replyPrior to LLMs I never considered that I might have to make a resource-usage decision between hiring Star Trek's Data vs. his stupider brother B4...
replyStar Trek is a post-scarcity society, those problems don't exist there unless you're in the middle of a crisis and on emergency power.
replyLLMs briefly seemed like this too, after subscriptions made the SOTA models too cheap to meter, but before they walked back on that and introduced quotas...