Ease of use is the big elephant-in-the-room issue for Matrix.

The only way I've found to join a room is the `/join` command. There's a GUI search, but it doesn't work.

Users have to pick their identity provider, their home server, etc. Lots of choices, scary messages, and generally annoying to set up. Services that depend on someone who is technically inclined setting things up never become widespread outside technical communities.

If users pick an unreliable server to connect to, or there's a network split, things break, just like IRC does.

There are several clients, all slightly different. It's up to the user to pick which one they want, when they've never used any of them and just want something to work.

It's better than IRC, but that bar is so low you'd have to bury it to get any lower.