>Only if you're a nerd. Took me 5 minutes to get started with Slack for our company and managing it is a piece of cake.
Slack requires you to make an account on their website, a new account for every Slack group. IRC you can just join - pick a nickname and type the server's address and you're in.
IRC is completely trivially easy to use, Slack is not.
Setting up an e-mail address and a password is not an incredibly complex task. I have 3 seperate slack groups that are set up just for friends to chat.
Besides which, on most IRC servers, you're going to be using NickServ anyway, which is more complex a flow than setting up a user on Slack.
Slack requires you to make an account on their website, a new account for every Slack group. IRC you can just join - pick a nickname and type the server's address and you're in.
IRC is completely trivially easy to use, Slack is not.