The desktop app integrates directly with your operating system’s notification center (Windows Action Center or macOS Notification Center). You get reliable, actionable alerts whether Teams is in the foreground or minimized to the system tray. You will never miss a "Hey, can you jump on a quick call?" message again. Irony alert: Running a browser to run Teams is a memory hog. Chrome or Edge already consume gigabytes of RAM for your other tabs. Adding a WebRTC-heavy application like Teams on top of that is a recipe for a sluggish PC.
Here is a look at what you gain by clicking that "Download desktop app" button. The most immediate difference is the notification system. Browser notifications are notoriously fickle—they disappear when you close a tab, get blocked by aggressive browser privacy settings, or simply fail to trigger.
While the web version is a convenient gateway for guest users or borrowed devices, committing to the full desktop installation unlocks performance, reliability, and features that the browser simply cannot match.