Bad results mapping BT.1886 SDR to HDR?

A user reported that tone-mapping BT.1886 SDR to HDR (currently done by linearly stretching the black point) produces very suboptimal results, especially for OLED displays with true black point. We might want to rethink our strategy of forcing a tone-mapping step and instead default the SDR black level to the target device black level (when known), which would fix this issue.