[rwmj]

I think the interesting thing about having protection in software is you can do things differently, and possibly better. Computers of yesteryear had protection at the individual object level (eg https://en.wikipedia.org/wiki/Burroughs_Large_Systems). This was too expensive to do in 1970s hardware and so performance sucked. Maybe it could be done in software better with more modern optimizing compilers and perhaps a few bits of hardware acceleration here and there? There's definitely an interesting research project to be done.

[mananaysiempre]

Sadly, even software-filled TLBs look to be a thing of the past. Apparently a hardware page-table walker is just that much faster? I’m not sure.

[rep_lodsb]

Why is that surprising? The trap into kernel mode alone would already take more cycles than dedicated hardware needs for the full page table walk.