I think the point is that we should enhance IRC or XMPP, or create a new federated and open protocol that supports the features and easy setup Slack offers. Users suffer when we create proprietary protocols and walled gardens. Can you imagine if someone using Google Mail couldn't send an email to to someone using a university, government, or Yahoo email address? It would be unacceptable. However, this is the situation we are in with real time messaging protocols. It's infuriating to me that developers are content creating these systems. It's unethical, in my opinion.