Voice? Really? In the communities I've hung around in (gamer & tech) it sits idle, unused. Curious why it keeps being placed front and center as a major feature, when people don't seem to actually want it.
IME, in large community servers (usually info dumps or LFG platforms like the video in the article) I almost never see it used. But in my smaller friend-focused Discord servers, there's always someone in the voice channels.
I think the greatest thing Discord did for gaming communities was make it so easy to get people together in a voice channel that everyone stopped using Skype. I tried for years to move people to Mumble/Vent/TS but it never stuck. But Discord managed to do it. I'd say voice is still the main feature that draws me and friends to the platform.
Discord is usually used in online games in which voice communication gives you a big advantage. In the Discord homepage it says "It's time to ditch Skype and TeamSpeak" which were the programs used for voice communication in online games.