I think discord became popular in the first place because it was so much better than the alternatives, at least for the gaming/ hanging out with friends use case.
Discord was initially competing with a bunch of self hosted stuff, vent/ mumble etc with higher barrier to entry and less features and Skype which was terrible.
Discord really became big because it had 0 obstacle onboarding. In an age of Skype, Ventrillo, Teamspeak and Mumble, all "installation" software with "server addresses" and "setup your user config", Discord shows up, says "press this link", and done, you're ready to go. Install link? No, it's in the browser. Account? No, you literally got a temp account made for you. You just talked. Yes, with a button in the corner that says "Claim this account" which just wants an email and a name, but point is, you didn't even have to do that much. This is why the comparison to it is IRC despite the two being so far apart, IRC was the only other chat software with this small of a barrier to entry.
Everything else about the featureset was copy pasted from Slack. No one cares about that part.
It's because of everybody there.
Currently no one is on Entire - the investor are betting they will be.