.withUnsafeMutableBufferPointer doesn't work either, for reference.

Has anyone indeed started this discussion? I can't find one, and I would very much like to understand the justification behind this limitation.

Beta 1 you mean, released October 27?

Oh holy crap you're right—I have also had this "Xcode eats all the memory" bug, but it seems the fix detailed in that link has given me my processors back. Thanks!