Speaking from being very early on the train for Discord, it also had an extremely solid userbase right from the start because much of the early pre-marketing pull into it was for raid groups in the then-new Final Fantasy XIV: A Realm Reborn. People really needed a chat client to coordinate a big number of players and it was totally free, functional, and new on the scene. It spread a ton in the community and the people working on it were players as well from what I remember, though it's been a long time. So as the game grew in popularity, and everyone who was in a large group was starting to use Discord more, it cemented friend groups that formed in the increasingly popular game along with the Heavensward release and helped solidify a foundation in the gaming community imo.
Discord's killer feature for my money has always been that ever user in a call gets a slider bar (and mute button) to control the volume they hear ever other individual user in the call
Zoom, in 2025, still makes you wait for the host to figure out which of the 30 other people has a dog incessantly barking or is causing the echo or has horrible feedback, and then try to talk them through fixing it before finally muting them.
We had that in Teamspeak/mumble/vent, but the chat functionality on those platforms were definitely an afterthought. Not a place you'd cultivate a community.
Teamspeak had a ton of friction. When I was playing FFXIV and made my discord account, someone literally just sent a link in the text chat of our Free Company, I opened it in browser, made an account and used it right there immediately. To timestamp this, it was the summer of 2015, a little under a decade ago, iirc.
Not sure about now, but back then Teamspeak meant installing an application, setting it all up, having someone in the Free Company (almost always more than the limit for a free server on TS at the time) pay for a server or self-host (even more friction). With Discord there was no debate or decisions, just one step: Click link, sign up.
Its killer feature was how frictionless it was to adopt initially. If I sent you a Discord link, back then you could just click it and be going in under a minute.
Same reason Zoom quickly took over video chat. It was so easy to use that you didn't have to convince your friends to sign up for it, you just sent them a link and it just worked.
Yeah, didn't even verify emails. I got a surprise discord account back in 2015 because someone else used my email. I guess this xkcd[1] applies to younger people too.
Those tools were all, comparatively, trash. Literally ALL of the gamer groups I was familiar with switched en masse. You can’t compare Mumble and Discord IMO. There was so much setup friction that anything was better than what we had at the time.
Gaming was becoming less and less the ___domain of the tech-savvy crowd, strongly curbing the public's appetite for such host-it-yourself services. Teamspeak/Mumble were already dying at the hands of (inferior) free/easy chat platforms like Steam & Skype, so it's really no wonder that Discord was able to swoop in and clobber all of them by simply being free and featureful.
