Why Is a ‘First-Come, First-Served’ Rule Difficult to Enforce on a Global Decentralized Network?

Enforcing a strict 'first-come, first-served' (FCFS) rule is difficult due to the decentralized nature of the network. Transactions originate from all over the world, and there is no single, universally agreed-upon time reference.

Transactions arrive at different nodes at slightly different times due to network latency. Furthermore, the FCFS rule conflicts with the economic incentive of validators to prioritize higher-fee transactions, making it technically challenging and economically undesirable to implement fairly.