Click the link, choose a nick and you are thrown into the chat. That way you could checkout a new community and discord in general with a really low barrier to entry.
The community that drew me to discord made the jump when their self-hosted IRC network became increasingly unstable. The multimedia features like easy picture sending ware also very nice, as was the mobile client.
Still dislike the condecending tone they have towards the users tho.
And I still use IRC on other networks. Both with a shell running irssi in screen and hexchat on my desktop that starts up with windows. That's for more ephemeral communities.
Matrix did not have "servers" (in the Discord sense) until very recently. It's also much harder to produce an open, federated protocol than a proprietary one so Matrix has been less featureful than Discord for a long time, but the gap is closing quickly.
There's also the matter of marketing: Discord is a product, Matrix is not, thus it's harder to market. Yes, now there's Element, which is a product, but given above, Discord has had an effective head start of several years.
Give it a bit more time.
The "popularity" reason does not explain the cause & effect timeline.
Discord was started 2015. But Matrix, XMPP/Jabber, IRC were older than that and thus by definition back in 2015, they were already more popular and well known.
Thus, the original first reason can't be popularity -- because there was a point when Discord was not popular and it was still chosen over Matrix & IRC. The reason is that it's easier for project maintainers to create new Discord servers + channels. E.g. : https://support.discord.com/hc/en-us/articles/204849977-How-...
Put a different way... What caused Discord to become more popular than Matrix? The obvious answer is that a few clicks on a web page is easier than installing and configuring a Matrix server. Is there really a better explanation than "ease of use"?
EDIT reply to: >Discord was first popular with gamers because it offered _good voice chat_; and this popularity drew in other communities.
I emphasized "good voice chat" because in that sentence, it's the more explanatory reason than just "popular". So the other and older alternatives like IRC did not have good voice chat. And this drives decisions of gamers that prioritize a desirable feature such as seamless VoIP over the need to use an open protocol (IRC) that's not owned by a corporation.
In other words, whenever the proposed reason for product dominance is "popularity" or "network effects", we always want to dissect that further and look for the reason that caused the rising popularity. If we don't, we just end up with infinite recursive reasoning such as "it's popular because of its popularity" -- which is not a satisfactory nor helpful analysis.