Getting distributed systems correct is very hard. Mainframe architecture allows one to program and deploy as if you had a giant computer with consistent transac

Getting distributed systems correct is very hard. Mainframe architecture allows one to program and deploy as if you had a giant computer with consistent transactions for the most part. Since banks were the early adopters of computation in large scale it’s clear why most still run on mainframe - the transition to cloud architecture isn’t a simple translation, you need to glue a lot of things together to the same levels of parallelism, and probably sacrifice some consistency that you get “for free” on mainframe architecture. Cloud is cheaper ($ per cycle) at the expense of human brain power to glue it all together.