Dear Erik,
Wiki is a poor source. DNG can contain both lossy and lossless raw data, and it can also contain linear demosaicked images. The tags that are pre-determined in DNG are not enough for many purposes. Say, one has a stitched sensor, like semi-MF or Nikon FX. Have you seen any DNG tags that control flat fielding? 2 matrices are not enough for many purposes as well, that is why the whole DCP thing was developed, and even that does not solve everything.