Stride was launched last year. I guess it didn't get much traction then if they gave up on it in less than a year. For consumer it is of course bit sad to see the 800lb gorilla just keep growing and eating up competition, but I can see how this makes sense to at least Atlassian; they are getting better Slack integrations, and possibly other partnership benefits for what seems like essentially free. Not sure how much this move will benefit Slack (the company, not the product), but maybe they'll absorb few more customers this way. Although I imagine many Hipchat/Stride admins will be reevaluating their choices instead of just jumping blindly to Slack.