[mike_hearn]

Your information is out of date.

Modern Qualcomm basebands are restricted by an MMU and isolated from the main OS. Carriers wanted this because baseband exploits were such a common way for phones to get rooted. Additionally they have been hardened considerably in recent times, apparently modern Qualcomm basebands are much, much harder to hack than they once were. And they run now on a proprietary CPU design called, I think, Hexagon, which makes even just disassembling the thing a bit tricky.

[mindslight]

I can believe this, because they do have an interest in preventing any random party from taking over a phone. Unfortunately, there is a large gap between being resistant to exploits, and convincing the world that you're resistant to exploits through open review.

BTW do you mean "rooting" in the longstanding sense of general exploitation, or in the recent narrow sense of the owner of a device obtaining control of it? There's of course an overlap between these two, but insight into the specific business motivation would be interesting.