Discord replaced everything else because it had far more features than Teamspeak. Teamspeak can only do voice chats amongst small groups of people in invite-only rooms.
Discord could do public facing discoverable communities with drop-in voice calls, group video calls, group screensharing to stream movies or gameplay to your friends or an entire community of hundreds, markdown enabled text chats. And each of those communities could have categorized collections of chat & drop-in voice rooms with granular permissions for different users, and more recently it added built-in forums as well.
It's truly a kitchen-sink approach, but the end result was the ability to create both small and large communities, all of which only needed a single account, and all of it streamlined so non-techies could easily use it.

