Because there was no agriculture or horticulture or cultivation before the patent system
John Roberts* during oral arguments in Bowman v. Monsanto:
Chief Justice Roberts: Why in the world would anybody spend any money to try to improve the seed if as soon as they sold the first one anybody could grow more and have as many of those seeds as they want?
And there you have it.
What we're up against. It's all about the rents, baby!