Additionally, they had the opportunity to capitalize on Campfire in a way that they could have closed the market for realtime collaboration before Slack. Obviously Slack is a superior product (and given 37signals opinionated product philosophy I don't think they would have ever built something so comprehensive) but still... they had a 7 year head start on Slack. A lot of orgs used Campfire every day, and probably plenty still do.

But I appreciate their commitment to focusing on one thing.