This is some more research based on prior efforts.
The goal is to make more efficient use of available RAM. If the system runs low on memory only two options are possible: either the kernel invokes the oom-killer to quit tasks to free memory (oom --> out of memory) or starting to swap.
Swap is a problem if it happens on slow media. 'Slow' media usually describes the situation on SBC. 'Average' SD cards (not A1 rated) are slow as hell when it's about random IO performan