Fine, I'll do it.
I took a picture I remembered had the problem in a particularly severe way. The picture was taken with a Canon 5D, not exactly exotic at the time. This with the process version of LR 4.4:
Original picture, default LR 4 rendering:
Default LR B&W rendering with all cursors to zero:
Branches on the right in the previous photo:
Sky darkened in LR:
Branches on the right in previous picture:
Pinetree trunk and branches:
Sky darkened with Nik Silver Efex Pro as a smart filter in PS:
Branches in previous photo:
Pinetree trunk in previous picture:
So there.