Re: The days before memory protection WAS (less) necessary...
I would like to call BS, at least on the Burroughs comments.
The B5500 and all of its children including the current lot, had/have hardware protection at the word level. Each word in memory has a a number of tag bits which tell the hardware what can be done with this word. Protection from over-write or read is at the segment level and again done with hardware segment limit registers which contain the storage limits accessible by the currently executing code. All code is marked execute only and data are separated into different segments depending on the compiler based definitions.
I think Bell and Newell cover this design but I'm old and can't remember the real technical stuff, just the fluff level I wrote above.