That isn't a flaw, it's a constraint, which applies to practically all databases. Good databases are the ones that can optimize around these constraints for arb

That isn't a flaw, it's a constraint, which applies to practically all databases. Good databases are the ones that can optimize around these constraints for arbitrary data analysis and manipulation (e.g., by caching, read-ahead, auto-indexing, deduplication, aggregation, batching, contention-avoidance etc. etc.) There's a lot more to data analysis than loading data off disk.