I'd say that there's a lot more to it than that. IRC isn't intuitive for new, modern users. Take login and password recognition using one of the many NickServ options, for example.
[1] https://client02.chat.mibbit.com/?channel=%237daystodie&serv...
Oh, you mean its easier for people who already have github account? Who are these people that create accounts on a hosting service for one of the more complicated version control systems but find connecting to ftp servers and entering cli commands too daunting?
If you want to talk about confusing, in gitter I can navigate to a room and see what happens in it but I need to press an extra button to actually be able to talk in it? What? Rooms, private chats and /me? Many parts of gitter doesn't make sense if you don't know the whole chat paradigm that irc created.
Gitter derives it utility purely in the better web client and its custom built integration with github.