Why is distributed consensus difficult to achieve?

WHY DISTRIBUTED CONSENSUS

so let us quickly go to the Consensus Algorithms: PAXOS, IBFT, and Raft algorithms so earlier you have looked into this concept of distributed consensus so in the case of a consensus algorithm well if there is only a single decision-maker you do not require any consensus.

whenever the other multiple decision-makers and in a collective way they want to come to a certain decision then you require the consensus

Reaching agreement in distributed computing
Replication of common state so that all processes have same view
applications:
Flight control system: eg. Boeing 777 and 787
Fund transferring system: Bitcoin and cryptocurrencies
Leader election/mutual exclusion
so the distributed consensus it helps you to reach an agreement in case of a distributed computing so in case in terms of the state machine replication concept you replicate the common state so that all the processes they have the same view of the state they can understand so if read more