Earlier quoted context omitted.
Ware patterns are a very long term effect. Hunter gathering was a seasonal diet so they would have eaten more grains in some periods and less in others. In areas with abundant natural grains it’s likely their diets did consist primarily of grains for some portion of the year. From a survival standpoint low effort and especially low risk calories are really hard to ignore.
There is nothing low effort about grains. They don't simply grow abundantly in nature without other animals eating them. In addition, before manual cultivation, wild, non selectively bred grains were nothing like modern grains.
But the thing with nuts is that they have multi year cycles to break the foraging ladder. Every few years the whole forest produces five times as many seeds as in a normal year, and then famine and predation pulls the nut eating population back down.
Only humans are clever enough to really exploit those patterns. A child would learn to make acorn bread, but couldn’t count on it being available except for short periods and then every so many years.
[edit to add] if memory serves, in the modern era we are down to some First Nations populations and Korea for cultures that still eat acorns regularly.