I would agree with you if the metrics were even close. Beef being like 100 times less efficient than legumes in many metrics makes it absolutely clear it’s better to grow legumes than beef, regardless if people want to consider, say, leather as a waste product.
This would be true if the foods weren’t so extremely far apart in terms of efficiency. The least efficient legumes are still much more efficient than the most efficient beef, per gram of protein. Please see table one in the largest meta study ever done on the topic below, constituting 38,700 farms and 90% global calories consumed (also included in the documentary): https://globalsalmoninitiative.org/files/documents/Reducing-food’s-environmental-impacts-through-producers-and-consumers.pdf