Except that even RAM isn't just RAM anymore. No one who cares about performance treats memory like a big random access array. With multi-level caches and sequential prefetch, RAM is more like disk blocks. Flash memory is even more so, with its relatively slow read start and very slow write.
When programmers don't understand and account for the underlying nature of the system, it results in awful code, like most Java software. So don't hide too much of it.