It's human nature to have one group not adopt certain advances, i.e. the Menonites with Electricity.
But it is also human nature to explore and expand, even to the point of leaving the tribe to do your own thing.
That a tribe chooses not to embrace certain cultural advances, is far different, from assuming that in 300,000 years ALL men would reject such obvious advances.
Now, I'm inclined to think domestication of farm animals came first before agriculture. Herders are a lot like their hunter forebearers in that they typically move around from seasonal camp to seasonal camp (c.f., the Mongols of central Asia). I read of one anthropologist who believes people did not equate sex to childbearing until after the domestication of animals, making the connection through years of observation. After that, it might have occured to them that plants did something similar.
Even after agriculture was discovered, it wouldn't have been terribly attractive. Raising crops is time consuming for the amount of nutrition garnered. Hunter/gatherers can typically acquire their daily requirement in calories in just a few short hours (two to four, according to some anthropologists). Farmers work from sun up to sun down -- and even after harvesting most crops require additional work (threshing) to be made edible. Skeletons of farming folk in Europe from about 9000 B.C. show their lives were typically short and extremely painful, especially among the females whose skeletons show evidence of long periods kneeling (probably while grinding grain).
Agriculture would not have been attractive, and was probably taken up when population pressures depleted ready supplies and forced people to begin to grow their own food or starve.
I once read an interesting interpretation of the Fall in Genesis, in which it was an allegory for the transition from the hunter/gatherer existence (food readily available, not really much to worry about) to farming with all its commensurate drudgery.