> but Amiga multitasking wasn’t memory-protected
This was not the case for Windows 95/98 and ME, either BTW IIRC. Only with Windows XP Microsoft introduced memory protection for the mass market.
Probably Windows NT rather, which turned into Windows 2000 (and then XP)
Windows 3.11 was pretty unstable, because it wasn't using protected mode. I remember how unstable the Macs were back then too before the introduction of OSX.
Applications also had to voluntarily give up control of the CPU, cooperative multitasking. That's bad when an application crashes and takes down everything with it.
No, Windows 95 had memory protection for 32-bit apps. Usually when a 32-bit app crashed, the rest of the OS worked fine.