Bitbucket is currently lagging behind Github/Gitlab in pretty much all areas. Usability-wise, even in its most basic features, it is simply terrible at the moment. And there is no social effect whatsoever - in fact, placing your stuff on BB right now is practically a declaration that you hate talking to people. It clearly is not a priority for its new owners (Atlassian).
Having been at a company that was a heavy Atlassian/Jira/BB user, it seems the only reason for companies to ever use BB was because they already used Jira, and/or because of pricing differences vs Github (although that has changed a few times since I've left there).
The only reason people pick them is because someone in the tech department got some sweet kickbacks on an expensive deal.