Potentially relevant piece of info, it was a Boeing. Might be bad maintenance, might be manufacturing defect, we’ll need to see what the investigation turns up. At the very least the fact it was a Boeing plane raises some eyebrows.
Edit: rereading it mentions it was a 33 year old plane with a history of problems. Leaning more towards bad maintenance, although if it was that prone to issues maybe it should have been taken out of service before now.