You call 50,000,000 buffalo “in check”?
The cycles of graze, move, graze, move, with seasons where plantlife had time to recuperate, are long gone. It's graze, graze, graze, until there's nothing left and the herd die out or are moved elsewhere to do the same.
The problem with this issue is it's complex in a bell curve nature. With humans in the mix, we take it to an extreme - it's either cattle land or its not, and there's no room for a compromise because cattle can't graze on cropland, or through urban/industrial areas, so they get put on lots too small for them and cause immeasurable ecological damage in the process.