Yep, you're absolutely right. I guess that maybe if you care about inventing new kinds of loops (e.g. a DSL that wants to loop as a specialized kind of `fold` c

Yep, you're absolutely right. I guess that maybe if you care about inventing new kinds of loops (e.g. a DSL that wants to loop as a specialized kind of `fold` construct), there's more flexibility with TCO. But Clojure shows that there's tons of mileage and composability that can happen by using runtime protocols and tasteful language-design decisions even without TCO. Capturing continuations is another interesting theoretical outcome of TCO, although as various scheme implementations show: the approach to supporting TCO also imposes some performance constraints on call/cc.