It's not abundant enough. When it was more scarce - more people starved. Starvation was common even in Europe till the end of WW2 (because after WW2 cheap artif

It's not abundant enough. When it was more scarce - more people starved. Starvation was common even in Europe till the end of WW2 (because after WW2 cheap artificial fertillizers were introduced). And that starvation happened mostly in unindustrialized countries (meaning - 90%+ of population worked in agriculture).