Earlier quoted context omitted.
It's worth noting that this particular plane was new. So 'poor maintenance' is not likely. I don't think anyone serious literally thinks that 'Boeing built a POS that fell out of the sky', but there are indications that they built a plane that required substantially different handling and tried to abstract that fact via the onboard systems, which makes the pilots unable to handle the actual behavior of the plane when…
I would consider pilots not being made sufficiently aware of the implications of a faulty AoA sensor a maintenance failure. Clearly people have fucked up because planes have crashed. We're basically just arguing over whether the responsibility split goes 33/33/33 or 20/20/60 or something else.
From what others have said, I gather there is a problem of this plane behaving differently than the rest of the family, which is being 'masked' by the on-board software so that it 'feels' similar to the other planes in a regular situation and thus requires minimal additional training. This however goes out of the window when the pilot cannot rely on the software and suddenly has to deal with how the plane 'really' behaves, which is substantially differently.
If that's the case, I'd consider the root of the problem to be significantly on Boeing's side.