The OOM killer is a “solution” to a very real, and sensible design choice: not committing physical memory and swap whenever address space is mapped - there are very good (and noticeable) reasons for not eagerly committing, but fundamentally if you have done so you have to decide what to do when you end up needing more physical space than is available.

Linux went down the “if a process is trying to do this, it must be important so I’ll prioritise it and kill something else”, and alternative is to kill that process when the commit fails.

Either is a valid option, the OOM killer ran against a regular desktop user’s idea of what is the correct course of action, but for a server it might not have been.

Problem is that something else might be actually performing a critical task.

The assumption being made is that the app going mad for memory is the critical one. Something has to die, and deciding which is hard.