Mempools, which are unique to each node within a blockchain network, pose a significant challenge in ensuring that all transactions are universally acknowledged and processed. The variability in transaction visibility across nodes underpins the argument against a proposed system that would mandate miners to prioritize older transactions. This approach is criticized for its potential to introduce regular chainsplits due to discrepancies in transaction recognition among nodes.

The critique further elaborates on the theoretical foundation of blockchain technology, emphasizing the reliance on mining as a mechanism to achieve consensus on transaction history. The inherent uncertainty in transaction visibility negates the possibility of a system where the chronological age and ordering of transactions could be universally agreed upon without the need for mining. This perspective underscores the complexity of achieving consensus in decentralized systems and the essential role of mining in maintaining blockchain integrity.