So it's not "literally no company". ;)
Disclosure: I work for Mozilla and I have reported a number of security bugs on our code, the vast majority of which are now public.
Regardless: that's a good point. I should have said, public disclosure of internal findings is not an industry norm. Mozilla is a good counterexample to the argument that everyone close-holds internal findings.
Of course, as you say, we do rate almost all security issues, and eventually make them public, so the information is only a bugzilla search away! https://bugzilla.mozilla.org/buglist.cgi?keywords=sec-critic...
Project Zero has long maintained that any serious company should be able to meet 90 day disclosure timeframe, and yet here comes Google+...