Slack is a web app too, it doesn't hold it back at all. Chat apps really don't need that much and the cross platform benefits of making a standalone webapp is

Slack is a web app too, it doesn't hold it back at all. Chat apps really don't need that much and the cross platform benefits of making a standalone webapp is numerous. Also being a chrome app means it can run on a chromebook, one of the most secure desktops out there. And it being open source makes it you probably could make your own native clone implementation if you were really so inclined.