In this article, it states that the quorum is not sufficient enough to solve the availability issue of the system due to its 2/N + 1 constraint of healthy servers.

However, does the leader/follower example work in conjunction with quorums, in that do we still need a certain number of reads/writes (R + W > N) done across the entire system?

According to this article: https://aws.amazon.com/builders-library/leader-election-in-distributed-systems/ it seems that the leader becomes a single source of failure in many aspects.

Also in the diagram posted, the leader handles all read/write request and then distributes the replica request to its follower, but doesn't this become a single source of failure that quorums aim to solve?