I don't know if it is reasonable, but that's what is always said. The primary argument for Linux popularity is always "Android!".

Also, in this context I think it's pretty relevant. My personal opinion is that if Slack was just an IRC client instead of having its own propertiary backend, it would have been a better product.

Of course! And by digging deeper, we can also establish that cellphones are popular, and that electronics are also popular. It's going the other way (away from generality) which lessens popularity, since you're targeting something _more_ specific.