This is a fine sentiment, but it's hardly a bright-line rule. We don't criticize Twitter's handling of abuse or fascists because they promised us a platform free of abusive fascists; Twitter didn't promise us shit except 140 character messages. All the problems were emergent.

So many of the great (financial) success stories of our sector are about startups stumbling into an untapped demand, and then running with it for as long as the money lasts. Nobody sets out to build a bridge – they build a 2x4 plank, and then realize that rather a lot of people want to walk on it.