It's really comically how many people here, including yourself, are just assuming they know more than then author. Kenji has done numerous studies debunking this and has dug into every single part of the burger making process and so much more to come up with these steps.

Flipping your burger less doesn't help. Yes, the salt level is correct. Yes, putting the grinder in the freezer is a good idea. Stop assuming you know more than experts without conducting studies your self, you arrogant people.