I love Immich and Sharkey but both use Discord. Sharkey even used Matrix in the beginning but eventually switched to Discord. I think their reasoning was that they were often attacked by trolls etc. and that Matrix didn't had good options for moderation etc.

And while I love Matrix I fully agree. Yes there are moderation bots like Draupnir and they're good but you will need to self host them and register a user for them and and and. It's not as easy as with Discord or even Telegram bots. Also there are many Discord bots providing very fun elements like levels, reputations, roles etc. which simply do not exist or aren't even possible in Matrix as it currently is.

On top of that we have the decentralization "problem" for end users who aren't technical. They simply don't care much about privacy and they don't care if Discord stores every single message and picture in clear text forever on their servers. It's easier to create a Discord account on a centralized platform than understanding Matrix understanding which server to choose, understanding which client to choose and understanding how encryption, key management etc. works. Yes decentralization is important and great but for the average user it's still something that they do not really know which "overcomplicates" it for them.

And another point is that Matrix spaces are simply not the same as Discord servers. Channels are not as easy to manage because they are rooms on their own in Matrix and a space is not a server but rather a way to organize multiple rooms. Not every client supports spaces yet. Clients implement them differently. Then there's Element and Element X on phones confusing people new to Matrix etc. In Discord several channels can be grouped in another category. In Matrix you'd use Subspaces for that giving you the same issue as with normal spaces.

And most clients don't implement simple things on mobile like...sending multiple images at once. From the perspective of an end user that fact annoys the heck out of anyone wanting to send several pictures.

So yeah I think it's a mixture out of those things.

Matrix especially needs better bot support with bots that could be used by everyone as it is with Discord instead of being only usable by server admins or the bots creators as it is with many Matrix bots. And it does need a better solution for spaces with rooms or another thing in the specs that replicates how Discord servers work so that it's a "space" with actual "subchannels" without every space technically being it's own room dangling around in limbo and just being "sorted" into the space.

And it needs better moderation tools.