I agree it's not an easy call between the two! I guess the conclusion of this episode could tip the scales, if we ever get an explanation.
My best guesses right now are some mix of organized crime disrupting their German distribution and/or less publically acknowledged graymarket/OEM channels gone wrong.
If it really comes from inside Seagate I don't think a sane person would buy from them again.
It gets more nuanced when talking about their responsibility to keep oversight over their supply chains and distribution.
https://en.wikipedia.org/wiki/ST3000DM001
(I had one, it died just after its warranty ended but Seagate did send me a replacement after bitching about it for long enough.)