That is more for "why it helps there in the first place" than any disparagement of the rainforests. That the soil is terrible is more reason to leave them there

That is more for "why it helps there in the first place" than any disparagement of the rainforests. That the soil is terrible is more reason to leave them there - especially when they provide steady rain. It isn't like temperate climates where you can rotate between farms, fields, and forrests over time easier.