It basically is. AFAIK, there’s no browser based way for steam chat, Google messages, or snapchat. I’m sure there are others too.
The biggest advantage I can think of is notification integration. The ‘tabs’ do give notification counts. You can minimize to the system tray so it doesn’t have to be open. It would be seperate from your web browser, so if you have 30 tabs open like I do it’ll be less cluttered. But it’ll send notifications to the desktop with snippets of the message, like a popup on your phone. Also, even if you clear all your cookies/browser history etc., since it’s seperate from the browser, you don’t have to worry about logging in again.