IMHO: I have yet to find a database that comes with any current business software that is fully normalized to 4NF in every physical data structure. After a quick rundown of what is in my current production environment many of them fail simply becuase they store duplicate denormalized historical data in the transactional database for reporting and auditing. We can talk all day long about how this could be done better, faster, stronger.
Actually I would expect historical data held for reporting to be denormalised, but I would also expect it to be in a separate MI database (I'm a dinosaur - I haven't learnt to type BI instead of MI). But the stuff for audit should be the stuff that was generated in real time by the real transaction so quite separate from reporting data.
I wonder how many of us have got anyone to agree to a massive budget needed to fully normalize.
Once a system that should be normalised has been built unnormalised, no one has budget to do proper normalisation until shortly after the brown stuff meets the blades.