Well, consistency and availability are the problem here. While enforcing one of the property, you lose on the other. Not sure how would you achieve those opposing properties without introducing huge amount of complexity.
In this case, replication consists of communication between 2 instances, and when one them fails you need to pick consistency or the availability.
Paxos and Raft introduce consensus using multiple instances communicating with each other to mitigate those problems. Implementing correctly communication with 2 instances is hard enough, implementing it correctly for n instances is for sure harder.
In Memgraph, we actually tried to implement Raft and we did manage to some degree, but the effort was too much, especially when you look at the results we got (protocol that didn't work for many edge cases).
In this case, replication consists of communication between 2 instances, and when one them fails you need to pick consistency or the availability.
Paxos and Raft introduce consensus using multiple instances communicating with each other to mitigate those problems. Implementing correctly communication with 2 instances is hard enough, implementing it correctly for n instances is for sure harder.
In Memgraph, we actually tried to implement Raft and we did manage to some degree, but the effort was too much, especially when you look at the results we got (protocol that didn't work for many edge cases).