> This is a transparent process that is not under control of the application. Thus, if any given memory access can block on IO from a disk drive, that means the system is fundamentally not real-time, therefore UI applications on such a system are fundamentally broken.

Not really. It means they chose to degrade performance when too much memory is used, rather than crash.

All options available when "out of memory" are bad. They thought that was the least bad option.