I just checked, and in 2019, they had $401MM in revenue with 1664 employees. That's ~$240,000 in revenue per employee.

Pinterest looks to have earned about $1.1 billion in revenue during the same time with roughly the same number of employees. Fastly is at $250MM in revenue with just 630 employees.

So it looks like Slack is at least twice as large as it should be for its given revenue. But why? Are they supporting too many platforms/devices? Or are chat applications just not that valuable to companies?