I think this issue isn't valid until there is proof of the cause. Humans make mistakes, it's inevitable and the adrenaline of the anticipation of flying adds to the problem. I was surprised in Hawaii when I was pumped about flying a certain area and I had a brain fart myself. When I started the motors one of the props flew off. WHAT? How could I have been so inattentive to not clip the prop on? I've installed DJI clip on props hundreds of times, and this time I messed up. $#it happens. I'm sure it's possible for someone to "think" they installed the battery firm enough, but got in a hurry and didn't. Did they pull at the battery after installation? That's part of my routine, I give it a good tug to make sure.
Another inspection routine to add to your list is to inspect all battery clips to insure the plastic lip isn't worn on each of the two battery clips. Also, check the lip of the craft battery compartment to insure it's not wearing out. If these surfaces are all OK, and you are diligent about securing the battery, and tugging it to make sure, you shouldn't have a problem.
I think many of the power loss scenarios are from ESC's that fail, bird strikes, or other reasons unrelated to a dislodged battery. I'm not saying the battery coming out can't happen, but it is rare IMO, considering the number of P4 craft flying every day around the world. This should be part of the P4P validation steps of new craft purchased, inspecting the battery compartment for integrity and sloppiness.