Implementing group messaging with Kafka

I’m trying to build a group messaging like below. I can make below architecture with redis pub/sub or grouping servers with consumer group. But if I group users with consumer group I think there’s no real good reason for using kafka since the performance wouldn’t that be great. Is there any other way to implement it better?

I don’t think each user would be in the same consumer group.

Also it would be good to understand more about why you think the performance wouldn’t be good?

I thought that every user(server) would be need to be grouped to Consumer group since I have to send all the servers exact same message.
Also I/Kafka don’t know which server User(Server) B, C are connected to.

Because of it, I was trying to use consumer group. Also I thought using consumer group would cause a lack of performance because each server’s “only one consumer” is handling the topic partitions which I expect is more than 100event/s.