The most impressive thing of all is Discord seemingly worked out stable audio/video years ago. I've had numerous calls on Discord which were more stable than calls through Slack, Zoom and even Facebook Messenger. The obvious choice for Discord is a professional offering, seeing as their core market is growing up with the product and largely probably in its late 20's, early 30's. I can see why Microsoft would have been interested, calls via Teams are like pulling teeth. Forget the terrible UI, the call quality (for me at least) through Teams has been atrocious and surprising given Microsoft have the resources to invest in making this component at least comparable to other products around.
Discord really needs to address the lack of server-specific avatars, though. Why can I change my username per-server, but I am stuck using the same avatar image for every server? Now that I use Discord for a wide variety of uses, I have needed this ability for a while now. Many of us have been crying out for this for years now.