The combination of: the absolutely terrible article being an obvious hit piece, the potential damage of the claims with almost no real evidence to back them up, and the complete lack of contrition or accountability.
I don’t think it ruined Bloomberg’s reputation entirely (I still love and frequently read Money Stuff), but it did eviscerate any credibility they had in highly technical, investigative technology reporting. And the refusal to admit the failures publicly definitely calls into question their editorial process and organizational culture.
Also, the idea that ‘thing x’ shouldn’t be criticized because ‘thing y’ is also bad is pretty clear “whataboutism” and an unhelpful way to address valid criticism.