I have a limited perspective but my experience was in getting acquired by a larger company that used Slack. In the larger company, especially when you first join, you don’t know who to talk to to get information you need or to coordinate work. This was partly due to the by design self service/decentralized culture of the company.

The use of channels was eminently useful then. You discover the general channel to use and then people that you didn’t previously know can help you. Also it doesn’t have to be a specific person helping you. Different people can help you at different times and with different questions. Likewise, you return the favor.

Also, you can then snoop in on a channel to keep track of areas you are interested in. This was a way of extracting and sharing institutional knowledge.

Lastly, you can create temporary channels for coordinating projects.

Although channels existed before, this was the first setting that I found it used extensively and effectively in this way. Perhaps most importantly to getting the whole system to work, there were cultural expectations placed on groups responsible for particular channels of being timely and helpful in replies.

Therefore you would get replies to questions in seconds or minutes. That was very useful in getting unblocked and unblocking others. You would almost never encounter the flame wars that you would see on Hacker News (well besides the social channels).

The organizational environment and the culture of how to use channels is what I mean when I say the innovation was cultural. Divorce channels from the environment or culture and you will see very different outcomes.