Interesting. Thank you for the correction. My misunderstanding was unfortunate because because AC mainline is certainly preferable to UA.

The general point, however, about choosing other airlines over Rouge stands. Last year this impacted my travel to KIN and MCO, on which I'd have normally flown AC but chose not to. The HNL example is another, although admittedly that's a points ticket not a paid fare.

My question also stands: Why do Rouge redemptions cost the same as mainline redemptions? It is supposed by a lower-cost option.

Of course I suspect I know the answer myself: Rouge is not lower-cost. It is a same-cost lower-quality carrier.