If we cut down the rainforest then how will pumping CO2 into the atmosphere grow it back again in a few days. With forest fires and logging forests are being destroyed quicker that they can regrow.
Plants are living organism and like all living organism there is a boundary to the amount of water, fertiliser and CO2 they can take in. In the case of CO2 they’ll let it back out into the environment, which means it will contribute to global warming.
It’s just common sense.