I think the wake turbulence is credible, for exactly the reason you said: if it was wake turbulence at the suggested 2800 ft. she'd just loose it and fall to the ground.... intact till impact
The aircraft did come down intact, other than the vertical stabiliser and the engines. As said on other posts, if the vert stab somehow came off, the wake turbulence could have caused a side slip, which would have torn off the engines, and resulted in the rest of the aircraft coming down in one place. Which is pretty much what the debris field indicates.
The wake turbulence is definitely a factor. Whether it caused the vert stab to come off or not is unknown, but once the vert stab was gone, wake turbulence, or indeed any unsettled air, would have led to the crash.
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