Some chemicals are good, yes, and if we're being really pedantic, everything is a chemical.
But there are some that, while improving initial yields, prove harmful to both land and living things over time.
There's a happy medium to be found.
And no, those comments are hyperbole. It's not going to be that bad.
But you've got to add in the cumulative deforestation that's happened globally as well. The Brazilian rainforest was one of the few enormous areas left relatively untouched, while the rest of the world cut their trees down.