Except it's not in this case, given Teslas are curbing wheels when in FSD mode. Not saying it's not impossible to fix this in software, but having parking cameras are a trivial way to address it.
It does have an accelerometer, but that is not enough for dead reckoning, it would also need a gyroscope. The accuracy matters too, given Tesla seems to tune to have a relatively small margin of error (not leaving a whole lot of space between wheels and curb, instead of turning wide). I'm skeptical an IMU would be able to beat a simple parking camera in this particular application (especially when your initial guesstimate of curb position may be wrong in the first place, and you get zero updates as you are making the turn given the cameras are completely blind to it).
It certainly helps for automated parking, which a tight right/left turn pretty much is the same thing. That's why parking cameras are implemented this way. If what you say was true, there would be no need for parking cameras.