What Slack has is a golden brand and a price point that apparently doesn’t make companies look much further than that.
It smells a lot like New Relic in that sense. Eventually the pricing catches up and new signups start dwindling and despite a good deal of lock-in companies think about switching.
Slack is immensely viral, in Silicon Valley it's basically used by almost every single tech person, its network effect is gigantic. When I glimpse at people's phones on public transportation, a large portion of folks are interacting with Slack. And that's not only used in startups, also in massive companies, both big "old" enterprises such as IBM as well as "new" enterprises like several FAANGs.
https://help.workspace.ibm.com/hc/en-us/articles/36001562237...