It's not speculation that BMW's approach has been to make a platform that can take multiple powertrains.
It's also not speculation that failing to optimize any platform for its powertrain will result in compromises of many types.
It's also not speculation that BMW's head brass squandered the technological lead BMW had when the i3 was introduced, even though the i3 platform was/is advanced, if too expensive for wider-market success:
https://www.latimes.com/business/la-...706-story.html
BMW has ample resources to engineer itself back to parity with best-in-class with regards to EV platforms, and they will, eventually.