Memory requirements for general-purpose desktop usage usually don't come down to a single task with a large working set that needs to fit in RAM in its entirety. It's more often a matter of the aggregate memory usage of many tasks, which means that in practice there's a wide gray area where the OS can make a difference, depending on the effectiveness of its memory compression, swap, signalling memory pressure to applications, suspending background tasks or simply having fewer of them in the first place.