Well Slack might have not worked for you. It doesn't work for everyone! Probably it works the worst for devs? Here is a story. I was working with a team of couple people located in different corners of the city. Everyone is remote except two who share an office. Up until a month ago everything was done over email. Sometimes you would send an email and get a reply in minutes, other times after hours. This was highly inefficient, to the point where I would call people to ask them to open emails... Guess what happened since we installed Slack and a couple of general open channels?