Don't get me wrong, I don't think the criticism is without merit... Like, I still don't run the standalone Slack app (on my desktop) and only run the browser version, because, like, why would I run two browsers?! (I'd make an exception for a really useful app like I make an exception for Java with IntelliJ's IDEs). But on the other hand, I also understand the author's point of view, and I definitely wouldn't berate him for it.