Roff  may be that kind of arcane evil we probably should eschew but it's morally closer to the typesetting machine. You tell it to select a reel of monotype font, move exactly (for this pointsize) some number of units and expose the mask to light at that point. It's a machine.

TeX targeted a theoretically pure model of the world, and grudgingly admits the practicality of having to approximate the perfect line by some bezier curve, but why requires a phd in theoretical maths and there's a queue of art historians out the door who are holding golden proportions curves shouting "you're doing it wrong".

TeX is a machine too but it's bytecode, not machinecode.

I think I hurled "when are you implementing OSI" abuse at your talks in AUUG meetings Chris, if you'd replied "never" it would have been wiser than your more temperate "later" response as I recall it.