Precisely; the reason for omitting many realistic elements is because they would be boring. If I wanted to play through all the steps of plowing a field, planting the grain, irrigating the field, dealing with weeds, harvesting the grain, and hauling it to a market to sell I would play Farming Simulator. If I'm playing a city builder, I'm perfectly okay with those steps being reduced to "plant crops, wait for crops to grow, harvest crops", and to have workers auto-assigned to those tasks while I'm laying out roads and palisades.

Also, having my village randomly wiped out from time to time by events beyond my control (plague, wars, etc.) would be realistic, but no fun at all in a game.