Just that we never did shit like that. It’s not something that needs an alternative explanation. People tend to assume that it was originally proposed as an explanation of our bipedal locomotion, but Krantz actually suggested it as an explanation for our big brains. He hypothesized that jogging after animals in the heat of the day (he never offered a reason for why this would have occurred only in the daytime) would have resulted in large numbers of neurons dying from heat overload, so a big brain would have allowed this neural death to happen without impairing cognitive function. This is why he proposed the endurance hunting at around two million years ago, when our brain size started increasing from chimpanzee size to modern human size, rather than around five million years ago, when our ancestors made the shift to full bipedality.

But the reasons behind the increased brain size have never really been so controversial as to require some weird explanation like this. We know that it wasn’t a simple overall increase in size, but was rather the result of an increase in the size of areas of the brain responsible for things like language and tool use, which leads to the easy inference that it was language and tool use that caused the increase in brain size.