> Presumably one intends to debug the code, when setting (debug 3). Then it'll be helpful to see the stack, no?

You don't necessarily need to give up TCO to do that though. You just do some bookkeeping and synthesize virtual stack frames. DWARF has native facilities to handle this.

CL goes the route it does mostly out of history, which includes the fact it has its own debugging ecosystem, more than any fundamental technical reason. There are technical hurdles with doing this in an image-based dynamic compilation model, but it's very far from intractable. Especially if you just do what GHC did and add a DWARF workflow. Most CL users wouldn't ever touch it though, because that's a drastically different debugging model that costs them a lot of ergonomic power, which may even be the reason they're working in CL to begin with.