They have rate limits, but they also want to control the nozzle, and not all their users use all their allocation all the time.

In reality, heavy subscription users are subsidized by light subscription users. The rate limits aren't everything.

If agent harnesses other than Claude Code consume more tokens than average, or rather, if users of agent harnesses other than CC consume more tokens than average, well, Anthropic wouldn't be unhappy if those consumers had to pay more for their tokens.