Seeds. What if every seed grew?

People like me, are often dismayed when seeds we have planted, fail to germinate and become a plant. Think for a moment.....what if every seed grew? Not just on your windowsill (I told you not to do that!), but in the world? Squish this thought down for a second. Think about all the trees, shrubs and other plants that are just  in your yard, or visualize a park you frequent. Each of those plants disperse seed every year. Thousands and thousands of seeds. If they all were successful and grew, we all would be swinging from vines like Tarzan........it would be a jungle, everywhere! You may not even notice all the seeds as the wind often blows the tree seeds around the county, and you know the neighbors dandelion is now in your yard.
We are lucky that many types of seeds are complicated to germ. There are several factors that have to come together correctly under certain conditions. This is what saves us. Although evergreens drop thousands of seeds tucked in 'pine cones' each year, seldom if ever, will a random evergreen start to grow. I wish some seeds were more complicated like thistle, dandelion, lamb's quaters, rag weed etc. It would make the life of the farmer much easier!