That's literally my point.

Marijuana has specific requirements as well, you can't just grow any seed into a plant and just harvest when it's ready. You have to separate male from female plants to keep the female from being fertilized by the pollen and grow seeds. They need proper nutrients, humidity, heat and light in order to grow. Then there's all kinds of things you need to know bout properly trimming them etc...

I read an article years ago about this, the whole male female plant thing was a big surprise to me. I picked corn as an example, because it's not as easy as something like zucchini, which grows like crazy.