What DSP were you using ?
FWIW, virtually all production music uses digital mixing and post processing.
MiniDSP SHD. I fully believe that some of the really, really, really good gear could do a lot better on it, but I am talking Theoretica and such.
As for mixing and such, there are a lot of issues with that as an argument.
1. Some of the really best recordings don't have it, but that is a very limited volume. Ex Octave's stuff and DSD from old tapes
2. Mixing and DSP are very different. Level mixing is simple. Parametric equalization is sometimes used in mixing but means the recordings had issues. Parametric timing changes are not done much at all in mixing. The latter two are in DSP, and are very complex and easy to screw up.
3. All the digital manipulation everywhere in the chain tends to introduce errors, and it adds up. I think a good analogy is freezing stuff. Sure - the fish you buy at the store has often been frozen before. But that does not mean that freezing it again at home and thawing it again is not going to make it worse.