> They came up with quorum queues which have less features and require to keep all messages in memory.

I don't think this is true

> Quorum queues store their message content on disk (per Raft requirements) and only keep a small metadata record of each message in memory. This is a change from prior versions of quorum queues where there was an option to keep the message bodies in memory as well. This never proved to be beneficial especially when the queue length was large.

https://www.rabbitmq.com/quorum-queues.html#:~:text=Quorum%2....