I don't think his point needs Slack to have a global network effect built in. I'd assume that, usually, a small handful of people in an organization decide on u

I don't think his point needs Slack to have a global network effect built in. I'd assume that, usually, a small handful of people in an organization decide on using Slack. Once the choice is made, network effects lock members in. Assuming the average org has 20 people or so, probably 90% of Slack's users are probably thanks to network effects.