With the current Canon sensors, theres is a real problem of banding noise in shadows and midrange, even without lifting dark areas. The red channel is especially critical. I had numerous shots ruined by that. So it's not only for revealing detail in shadows, but also in pictures with dynamic range that should be handeld just fine by this sensors.
That's because Canon's still relying on 12-year-old technology (especially with regards to off-chip A/D conversion), while everyone has moved on. It was revolutionary when it first came out, but is now truly dated.
The thing is, on comparing high-ISO performance, where the predominant source of noise is shot noise, rather than read or pattern noise as is the case at low ISOs, Canon actually has a small lead there. By extrapolation, this means that, were Canon to use column parallel A/D conversion like everyone else, the Canon sensors would actually have better DR than the Sony Exmor sensors!