Why is unstructured control-flow better for applying algorithms than structured control flow? That seems counter-intuitive to me. With structured control-flow

Why is unstructured control-flow better for applying algorithms than structured control flow? That seems counter-intuitive to me. With structured control-flow I can do things like reason about the level of nesting of the loop that I'm in. I can peel a loop iteration by literally saying 'take this loop here - copy the body of it out'. For context here's the kind of structure we use https://chrisseaton.com/truffleruby/basic-graal-graphs/#loops https://chrisseaton.com/truffleruby/basic-graal-graphs/#loop....