@mint NT was an offshoot of Carnegie Mellon's Mach Microkernel. Basically, Microsquish hired everyone they could who mattered away from that effort. NeXT adopted Mach which seemed to fuel it all.
Linux responded by trying to just make a better monolithic system, which is damned interesting. Mostly coz they've succeeded.
All this memory protection stuff is overrated. Mostly, unless you download "apps" all over the place, it's the web browser you need to keep in a sandboxed memory range.