I disagree. Thieves in 1e typically used d4/d6 type weapons. Backstab typically required a lot of prep work to land, what with needing to be behind and the target being unaware. I've only seen a 1e backstab happen in the first round of combat, afterwards the bad guys were aware of the rogue typically negating backstab (ignoring invisibility to reset that ability). A mid level rogue could (if they hit) do 2d4 or 3d4 damage + Str and Magic for one hit per combat. In they games I typically played in, bonuses weren't multiplied but I saw other tables treat it differently.
A fighter would have a d8 or d10 weapon. Also, they'd have bonus damage from Str and Weapon Spec. A mid level fighter would be attacking a 3/2 or 2/1. If we're comparing mid level fighter vs. thief, assuming everyone hits, 3d8 + (3*(Str+WSpec+Magic)) over two rounds where a thief would pull 3d4+1d4 +(2*Str+Magic). If memory serves (it's been a while), that would be an average for the fighter over two rounds ~28 damage, while the thief has 14 (assuming +2 weapon, +1 Str bonus for fighter, no Str bonus for thief). If you factor in hit chance, it skews even more to fighter with better THAC0 and hit bonuses for str and specialization.
At top levels, when the fighter gets 4 attacks every two rounds and the thief gets x5 backstab, it slants slightly more to the thief, but not enough to make a thief provide more damage over the fighter (for combats longer than 1 round).
I state all this, being my own personal experience. Backstab, sneaking, and other thiefly acts were notoriously dependent on DM interpretation and ruling, so you're experience might be completely different. If your DM was pretty accommodating in granting backstab to lead off an encounter, and then have another opportunity to land a backstab in the encounter, then yes, thieves might have been kings of dps
in your game. That was never my experience. I never saw more than one backstab land in a combat, and unless that backstab began and end the encounter, it was always the steady damage of the fighters that topped the dps charts. I did see an elven M/T once try to reset awareness by casting invisibility, and then promptly missed on her second backstab after a couple rounds of positioning. She decided after that there were better uses for her spells.
And really, in this crowd (EN world) I think it's less we're too young to have played early editions, and more we're all too old to accurately remember.