British Airways has devalued their mileage in a major way. They’ve built a system that rewards paid full fare business and first class passengers who want to redeem their miles for short haul economy. They’ve made status harder to earn. And the truth is that once you earn it, it isn’t very valuable.
Indeed, even a British Airways Gold member who primarily flies BA and lives in London even would likely be better off flying the airline but crediting their trips to American AAdvantage.