Plain Matrix rooms are a bit too foreign to Discord users i’d say.
There’s another alternative being built which resembles Discord a lot more, is federated and as i understand is built around Matrix communities: https://github.com/commune-os/commune-server
Here’s a demo instance: https://shpong.com/
Maybe i misunderstood your question but i’ve also heard many say they weren’t getting all the content from the channels they subbed to exactly on the subscriptions feed. Personally i’ve never noticed this but that’s why some channels started recommending to also hit the bell.