Its a lifestyle change not a diet. I was brought up as a low carber (without knowing it) and it been my lifestyle since a kid.. Now 50+. So it is totally possible. I only recently realused I was "classified as a low carber" and realised I should add fat in to my diet, thanks to info on this forum.
The low fat, which soon ended up as being high sugar, craze only started 30-40 years ago.
Also note that "low carb" is typically defined relative to current guidelines. Depending on the person even 1960's "normal" could still be too much.
(How many men ate a third of a kg or women ate a quarter of a kg of glucose per day 50 years ago?)
Absolute amounts or amounts relative to (lean) body mass may be a better metric for dietary sugars. (Rather than the proportion of "calories" idea.)