My friend group made the same jump. People forget just how abysmal VOIP was back then: your options were Skype, which had sound quality somewhere between "2 cans and a string" and "that one CD that you still try to listen to despite your brother cleaning it with the wrong side of the sponge" and RAM usage that was simply insane for the time period, or Mumble, where the sound quality was fantastic and used next to no memory, but had an interface and new user on boarding process that left no-doubt of its FOSS status, and purely ephemeral text chat.

Then along comes Discord. Easy to use, a master class in UI design, and sound quality that was at least in the ballpark of Mumble's. And persistent text chat! If you're going to be talking in Discord, it's only natural that some amount of conversation is going to spill over into the text channels. And if there's a lot of chat in those text channels, then it's going to suck conversation out of your other text mediums. That's how we ended up with Discord dominating the online community space.