8086 didn't have the instruction set to do preemptive, and the 286's memory model was 64kb pages... and barely good enough. The enabler for MPC (Multimedia PC) was the combination of 386 (and 386sx) + 16 bit sound card + CDROM + PCI VGA+.
Can you elaborate of that?
AIUI all you need is interrupts (CPU has them) and a timer (the PC platform has them).
Just for accuracy: Win3.x had pre-emptive multitasking. However, it could only preempt DOS apps. Win16 apps could not be pre-empted.
This compares quite closely to the FOSS RISC OS for Arm machines, which can preempt CLI apps in a "task window", but GUI apps only multitask cooperatively.
Co-op multitasking is faster and more memory efficient. That's why Acorn and MS chose it. But it's very vulnerable to a single app failing to relinquish control, locking up the OS.