That probably came across wrong. What I meant was that the ability to do concurrent access is the important thing, not the performance of it. CPUs aren't any go

That probably came across wrong. What I meant was that the ability to do concurrent access is the important thing, not the performance of it. CPUs aren't any good at contended access to memory cells, but they still allow it and it works. If you want your system to scale to many threads you need to break the sharing. Same with databases. The important thing is that it gives you strong consistency when there is contention. It'll never be as performant as operating on different rows concurrently though. When you touch different rows, you don't feel the pain of locking, which is the common case.