When diversity activists began campaigning a few years ago for tech companies to disclose their employee demographics, the truth was revealed. What resulted was a lot of handwringing over the state of diversity in tech and some commitment from companies, including Twitter to do better. Sadly, few companies have moved the needle. But for Twitter, that failure could be its undoing. Worse, for would-be tech workers, if a company with Twitter’s user profile can’t get diversity right, there’s little hope for the sector overall.