It seems very unfair to the thousands of people who have donated time, money, and services to IRC over its life span to dismiss it as not having gotten value.
It is not an obscure fact that investing shitton of money in marketing will yield better adoption than investing the same money in the product. People "who have donated time, money, and services to IRC over its life span" generally focused on the technical side.
You misunderstood. I am saying IRC would be as easy as slack if the slack team spent the time working on IRC. Their investors would never let them even if they wanted to.