This article misses the main reason people omit information: to avoid embarrassing others.

I always talk about how Xobni Analytics failed, for example. Recently I've been talking a lot to others about my own weaknesses.

But by necessity most of the stories about Xobni involve other people, and the stories often involve internal conflict among some of the people on the team, and to tell those stories properly would require being honest about others' weaknesses as well. There's not a culture of doing that in public settings, and I don't expect that to change.

EDIT: the two exceptions that prove the rule are High Stakes No Prisoners by Charles Furgeson, and some of Steve Blank's recent blog posts, even though Steve doesn't name names. AFAIK, both of these guys are basically retired from the valley.