BMW has X-Drive and Audi has Quattro, both produce sedans with traditional engines (non-boxer) and AWD. Dodge/Chrysler had(have?) an AWD version of the Charger/300, which is a large RWD sedan platform, I believe there have been others.
It's not that Subaru is the only game in town, it's that they've made it their only game, and have subsequently become synonymous with AWD despite Audi being at it for longer (Quattro has been around since 1980, full-time SAWD didn't come from Subaru until 1986).
GM has done some weird crap. Who else, with a mid-sized SUV, has gone this route? The WK and WKII both managed to do AWD with a variety of engine options without this nonsense, as did Ford with the Explorer. The Trailblazer and Envoy with this setup really had me like
View attachment 188533