you are misunderstanding. you're given a state of accounts and it has "correct" signature (according to a third party) - without verifying every transaction tha

you are misunderstanding. you're given a state of accounts and it has "correct" signature (according to a third party) - without verifying every transaction that contributed to building that state you cannot be certain it doesn't contain invalid records. merkle has nothing to do with it, you either verify or you trust a third party. checkpointing ethereum state or checkpointing bitcoin utxo set is a way to trade away security, decentralization and trustlessness for faster bootstrap. and ethereum folk have become way to relaxed about that fact.