If Xbox was throwing in the towel on ever again reviving the brand as it was, ever again being one of the big 3, then yeah, it would be stupid to not release on every platform and to not market on every platform. Asha right from day one has not indicated any sort of plans to throw in the towel and go the Sega route, she has been laying out her vision all along, Xbox hardware at the center, a return to affordability for consumers with a range of price points, re-evaluating what is exclusive and what is multiplatform, a return of focus to the core fanbase that had been cast to the wayside to focus on new markets, but not totally abandoning the attempt to grow through those new market opportunities. If she was brought in to lead Xbox through it's swan song years of decline, she sure has done a good job of misleading everyone, even the hardware division employees have reportedly felt revitalized after talking to her, after feeling like their days at Xbox were numbered before.
As long as Xbox is still focused on hardware, which Asha has indicated they still are since she said Xbox hardware was at the center of her vision, it just doesn't make sense to market to consumers that their games will also release on other consoles, because that is a surefire way to finish off Xbox hardware for good. Makes even less sense to release all of their games on other consoles as well, which I'm sure is why she said exclusivity would be re-evaluated, after all 3 of Xbox's big 3 franchises released games for PS5 or were announced for PS5 (Halo, Gears, Forza).
