There is some truth to this, no doubt.
Back in the mid to late '80's it was considered best to eat a shitload of carbs. I used to eat 6 meals a day which consisted mainly of pastas, tuna sandwiches, steaks-with pasta and baked patatoes. We kept our fat intake down to almost nil.
We trained 3 days on one day off, doing a split routine of 2 bodyparts per workout. For cardio we played 2-3 hours of tennis almost daily.
At that time I was between 27-30 years old, and I was 5'10.5 inches tall, weighed 190 lbs and was totally shredded...picture a lean roast wrapped in saran-wrap. I don't know what body fat I was, but it was in single digits for sure.
The odd thing is, that we didn't eat a heck of a lot of protein, but tons of carbs.